diff --git a/01-one.html b/01-one.html
index 74f33589db1c6fc450afeae82e1615066bc672bc..d4f31cf34b9af6b425cc49ff25a25732e2101dc3 100644
--- a/01-one.html
+++ b/01-one.html
@@ -28,7 +28,7 @@
<div class="col-md-10 col-md-offset-1">
<h1 class="title">Lesson Title</h1>
<h2 class="subtitle">Topic Title One</h2>
-<div id="learning-objectives" class="objectives panel panel-warning">
+<section class="objectives panel panel-warning">
<div class="panel-heading">
<h2 id="learning-objectives" class="objectives panel panel-warning"><span class="glyphicon glyphicon-certificate"></span>Learning Objectives</h2>
</div>
@@ -38,7 +38,7 @@
<li>Learning objective 2</li>
</ul>
</div>
-</div>
+</section>
<p>Paragraphs of text — possibly including <a href="reference.html#key-word-1">key word 1</a> — mixed with:</p>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python">some code:
to be displayed</code></pre></div>
@@ -47,27 +47,27 @@ from
program</code></pre>
<pre class="error"><code>error reports from program (if any)</code></pre>
<p>and possibly including:</p>
-<div id="callout-box" class="callout panel panel-info">
+<aside class="callout panel panel-info">
<div class="panel-heading">
<h2 id="callout-box" class="callout panel panel-info"><span class="glyphicon glyphicon-pushpin"></span>Callout Box</h2>
</div>
<div class="panel-body">
<p>An aside of some kind.</p>
</div>
-</div>
+</aside>
<p>or an image from the <code>figs</code> directory:</p>
<div class="figure">
<img src="fig/example.svg" title="this is the image's alt text" alt="this is the image’s title" />
<p class="caption">this is the image’s title</p>
</div>
-<div id="challenge-title" class="challenge panel panel-success">
+<section class="challenge panel panel-success">
<div class="panel-heading">
<h2 id="challenge-title" class="challenge panel panel-success"><span class="glyphicon glyphicon-pencil"></span>Challenge Title</h2>
</div>
<div class="panel-body">
<p>Description of a single challenge. There may be several challenges.</p>
</div>
-</div>
+</section>
</div>
</div>
</article>
diff --git a/02-two.html b/02-two.html
index 2dd346afadb25566b553b1b6d636e494f1989557..f04db2701693e508aff62fe71b46761279e7c906 100644
--- a/02-two.html
+++ b/02-two.html
@@ -28,7 +28,7 @@
<div class="col-md-10 col-md-offset-1">
<h1 class="title">Lesson Title</h1>
<h2 class="subtitle">Topic Title Two</h2>
-<div id="learning-objectives" class="objectives panel panel-warning">
+<section class="objectives panel panel-warning">
<div class="panel-heading">
<h2 id="learning-objectives" class="objectives panel panel-warning"><span class="glyphicon glyphicon-certificate"></span>Learning Objectives</h2>
</div>
@@ -38,7 +38,7 @@
<li>Learning objective 2</li>
</ul>
</div>
-</div>
+</section>
<p>Paragraphs of text — possibly including <a href="reference.html#key-word-2">key word 2</a> — mixed with:</p>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python">some code:
to be displayed</code></pre></div>
@@ -47,22 +47,22 @@ from
program</code></pre>
<pre class="error"><code>error reports from program (if any)</code></pre>
<p>and possibly including:</p>
-<div id="callout-box" class="callout panel panel-info">
+<aside class="callout panel panel-info">
<div class="panel-heading">
<h2 id="callout-box" class="callout panel panel-info"><span class="glyphicon glyphicon-pushpin"></span>Callout Box</h2>
</div>
<div class="panel-body">
<p>An aside of some kind.</p>
</div>
-</div>
-<div id="challenge-title" class="challenge panel panel-success">
+</aside>
+<section class="challenge panel panel-success">
<div class="panel-heading">
<h2 id="challenge-title" class="challenge panel panel-success"><span class="glyphicon glyphicon-pencil"></span>Challenge Title</h2>
</div>
<div class="panel-body">
<p>Description of a single challenge. There may be several challenges that make reference to <a href="01-one.html#challenge-title">Challenge Title</a>.</p>
</div>
-</div>
+</section>
</div>
</div>
</article>
diff --git a/index.html b/index.html
index 00e3cd75cf3e2c65fdf6b330e05de8e96a751301..c84f507ed6f504c6f4c033fe1c088642d0fc6337 100644
--- a/index.html
+++ b/index.html
@@ -29,14 +29,22 @@
<h1 class="title">Lesson Title</h1>
<p>Paragraph of introductory material.</p>
-<div id="prerequisites" class="prereq panel panel-warning">
+<section class="prereq panel panel-warning">
<div class="panel-heading">
<h2 id="prerequisites" class="prereq panel panel-warning"><span class="glyphicon glyphicon-education"></span>Prerequisites</h2>
</div>
<div class="panel-body">
<p>A short paragraph describing what learners need to know before tackling this lesson.</p>
</div>
+</section>
+<section class="getready panel panel-warning">
+<div class="panel-heading">
+<h2 id="getting-ready" class="getready panel panel-warning"><span class="glyphicon glyphicon-check"></span>Getting ready</h2>
+</div>
+<div class="panel-body">
+<p>A short paragraph describing what learners need to do before tackling this lesson.</p>
</div>
+</section>
<h2 id="topics">Topics</h2>
<ol style="list-style-type: decimal">
<li><a href="01-one.html">Topic Title One</a></li>
diff --git a/reference.html b/reference.html
index 921171eeb6b0eee9298c6d6ea6b78d1303d84191..6389da71d480e1fbe7a2c6b01bda136d4ac861f2 100644
--- a/reference.html
+++ b/reference.html
@@ -38,7 +38,7 @@
<dd>Definition of first term
</dd>
<dt><span id="key-word-2">key word 2</span></dt>
-<dd>Definition of second term
+<dd>Definition of second term that continues in another line
</dd>
</dl>
</div>