Set the id attribute by typing ="teacher".

<body>
<h3>Improv Tonight</h3>
<p id="teacher">
Improv lessons by Donatien.
</p>
<p>
Improv your way out of <em>any</em> situation.
</p>
<script>
</script>
</body>
</html>]]>

Make sure to type ="teacher".