diff --git a/01-rstudio-intro.html b/01-rstudio-intro.html
index 97313d322..b72730757 100644
--- a/01-rstudio-intro.html
+++ b/01-rstudio-intro.html
@@ -930,7 +930,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1210,7 +1210,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb64">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1264,7 +1264,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1303,7 +1303,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1334,7 +1334,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
diff --git a/04-data-structures-part1.html b/04-data-structures-part1.html
index d034473a0..5eeb6ff91 100644
--- a/04-data-structures-part1.html
+++ b/04-data-structures-part1.html
@@ -816,7 +816,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -1041,7 +1041,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Tip 1.1</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -1073,7 +1073,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Tip 1.2</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -1112,7 +1112,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -1125,7 +1125,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul><li>Weight is expressed on a continuous scale (real numbers). The R data
 type for this is “double” (also known as “numeric”).</li>
@@ -1157,7 +1157,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -1195,7 +1195,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -1385,7 +1385,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1609,7 +1609,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -1652,7 +1652,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Solution to Challenge 4</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -1840,7 +1840,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2100,7 +2100,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -2144,7 +2144,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -2184,7 +2184,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2234,7 +2234,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
diff --git a/06-data-subsetting.html b/06-data-subsetting.html
index 3a0239e15..73edbab0b 100644
--- a/06-data-subsetting.html
+++ b/06-data-subsetting.html
@@ -694,7 +694,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -881,7 +881,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1134,7 +1134,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul><li>The <strong>wrong</strong> way to do this problem is
 <code>countries==seAsia</code>. This gives a warning
@@ -1415,7 +1415,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -1560,7 +1560,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1624,7 +1624,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1778,7 +1778,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal"><li>Extract observations collected for the year 1957</li>
@@ -1850,7 +1850,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li><p><code>gapminder</code> is a data.frame so needs to be subsetted
 on two dimensions. <code>gapminder[1:20, ]</code> subsets the data to
diff --git a/14-tidyr.html b/14-tidyr.html
index 77655a64e..da0a8beca 100644
--- a/14-tidyr.html
+++ b/14-tidyr.html
@@ -464,7 +464,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The original gapminder data.frame is in an intermediate format. It is
 not purely long since it had multiple observation variables
@@ -656,7 +656,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -952,7 +952,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
diff --git a/aio.html b/aio.html
index 06cb776a8..c9ab300db 100644
--- a/aio.html
+++ b/aio.html
@@ -1015,7 +1015,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1300,7 +1300,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb64">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1354,7 +1354,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1393,7 +1393,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1424,7 +1424,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
@@ -2766,7 +2766,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -2996,7 +2996,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Tip 1.1</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -3029,7 +3029,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Tip 1.2</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -3071,7 +3071,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -3084,7 +3084,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul>
 <li>Weight is expressed on a continuous scale (real numbers). The R data
@@ -3118,7 +3118,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -3157,7 +3157,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -3348,7 +3348,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3578,7 +3578,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -3623,7 +3623,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Solution to Challenge 4</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -3814,7 +3814,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4075,7 +4075,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -4119,7 +4119,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -4161,7 +4161,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4213,7 +4213,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
@@ -5347,7 +5347,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5540,7 +5540,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5795,7 +5795,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul>
 <li>The <strong>wrong</strong> way to do this problem is
@@ -6086,7 +6086,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -6232,7 +6232,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6296,7 +6296,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6461,7 +6461,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal">
@@ -6545,7 +6545,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li><p><code>gapminder</code> is a data.frame so needs to be subsetted
@@ -11160,7 +11160,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The original gapminder data.frame is in an intermediate format. It is
 not purely long since it had multiple observation variables
@@ -11353,7 +11353,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -11650,7 +11650,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
diff --git a/instructor/01-rstudio-intro.html b/instructor/01-rstudio-intro.html
index 0ca9d6517..67660aaaf 100644
--- a/instructor/01-rstudio-intro.html
+++ b/instructor/01-rstudio-intro.html
@@ -932,7 +932,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1212,7 +1212,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb64">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1266,7 +1266,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1305,7 +1305,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1336,7 +1336,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
diff --git a/instructor/04-data-structures-part1.html b/instructor/04-data-structures-part1.html
index bb52c1917..193f5eaec 100644
--- a/instructor/04-data-structures-part1.html
+++ b/instructor/04-data-structures-part1.html
@@ -818,7 +818,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -1043,7 +1043,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Tip 1.1</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -1075,7 +1075,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Tip 1.2</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -1114,7 +1114,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -1127,7 +1127,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul><li>Weight is expressed on a continuous scale (real numbers). The R data
 type for this is “double” (also known as “numeric”).</li>
@@ -1159,7 +1159,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -1197,7 +1197,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -1387,7 +1387,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1611,7 +1611,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -1654,7 +1654,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Solution to Challenge 4</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -1842,7 +1842,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2102,7 +2102,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -2146,7 +2146,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -2186,7 +2186,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2236,7 +2236,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
diff --git a/instructor/06-data-subsetting.html b/instructor/06-data-subsetting.html
index dc00a2843..67aff92b3 100644
--- a/instructor/06-data-subsetting.html
+++ b/instructor/06-data-subsetting.html
@@ -696,7 +696,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -883,7 +883,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1136,7 +1136,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul><li>The <strong>wrong</strong> way to do this problem is
 <code>countries==seAsia</code>. This gives a warning
@@ -1417,7 +1417,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -1562,7 +1562,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1626,7 +1626,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1780,7 +1780,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal"><li>Extract observations collected for the year 1957</li>
@@ -1852,7 +1852,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li><p><code>gapminder</code> is a data.frame so needs to be subsetted
 on two dimensions. <code>gapminder[1:20, ]</code> subsets the data to
diff --git a/instructor/14-tidyr.html b/instructor/14-tidyr.html
index 901c99eb3..d3091518f 100644
--- a/instructor/14-tidyr.html
+++ b/instructor/14-tidyr.html
@@ -466,7 +466,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The original gapminder data.frame is in an intermediate format. It is
 not purely long since it had multiple observation variables
@@ -658,7 +658,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -954,7 +954,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
diff --git a/instructor/aio.html b/instructor/aio.html
index 4e2aefddd..c7d2bf80e 100644
--- a/instructor/aio.html
+++ b/instructor/aio.html
@@ -1018,7 +1018,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1303,7 +1303,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb64">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1357,7 +1357,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1396,7 +1396,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1427,7 +1427,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
@@ -2772,7 +2772,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -3002,7 +3002,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Tip 1.1</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -3035,7 +3035,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Tip 1.2</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -3077,7 +3077,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -3090,7 +3090,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul>
 <li>Weight is expressed on a continuous scale (real numbers). The R data
@@ -3124,7 +3124,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -3163,7 +3163,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -3354,7 +3354,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3584,7 +3584,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -3629,7 +3629,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Solution to Challenge 4</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -3820,7 +3820,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4081,7 +4081,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -4125,7 +4125,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -4167,7 +4167,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4219,7 +4219,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
@@ -5355,7 +5355,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5548,7 +5548,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5803,7 +5803,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul>
 <li>The <strong>wrong</strong> way to do this problem is
@@ -6094,7 +6094,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -6240,7 +6240,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6304,7 +6304,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6469,7 +6469,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal">
@@ -6553,7 +6553,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li><p><code>gapminder</code> is a data.frame so needs to be subsetted
@@ -11176,7 +11176,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The original gapminder data.frame is in an intermediate format. It is
 not purely long since it had multiple observation variables
@@ -11369,7 +11369,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -11666,7 +11666,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
diff --git a/pkgdown.yml b/pkgdown.yml
index 28a2014a2..51cdda3c3 100644
--- a/pkgdown.yml
+++ b/pkgdown.yml
@@ -2,5 +2,5 @@ pandoc: 2.19.2
 pkgdown: 2.0.7
 pkgdown_sha: ~
 articles: {}
-last_built: 2024-01-28T06:41Z
+last_built: 2024-01-28T15:45Z