The template book comes with placeholder content that’s fine but not very interesting to edit. Let’s replace a chunk of it with a short lesson you can actually work with.
Find the first <section> inside the first <chapter>. Select everything from the opening <section> tag through its closing </section>, and replace it with the block below.
<section xml:id="sec-right-triangles">
<title>Right Triangles</title>
<p>This short lesson introduces right triangles and
the Pythagorean theorem.</p>
<definition xml:id="def-right-triangle">
<statement>
<p>A <term>right triangle</term> is a triangle
with one angle measuring exactly 90 degrees.</p>
</statement>
</definition>
<p>The Pythagorean theorem states that
<m>a^2 + b^2 = c^2</m>, where <m>c</m> is the
length of the hypotenuse.</p>
<example>
<title>A 3-4-5 triangle</title>
<statement>
<p>Show that a triangle with sides 3, 4, and 5
is a right triangle.</p>
</statement>
<solution>
<p>Check: <m>3^2 + 4^2 = 9 + 16 = 25 = 5^2</m>.</p>
</solution>
</example>
<exercise>
<statement>
<p>Find the length of the hypotenuse of a right
triangle with legs of length 5 and 12.</p>
</statement>
</exercise>
<p>For a reminder of the terminology,
see <xref ref="def-right-triangle"/>.</p>
</section>
If you have a few extra minutes, change the topic to something you actually teach. Swap the definition, rewrite the example, replace the exercise. The structure stays the same; only the content changes. This is the authoring rhythm you’ll use for everything you write in PreTeXt from here on out.
