title: jquery, selector for class within id
body: <p>Below, how should I select the elements that contain the class <code>my_class</code> within the element with <code>id = "my_id"</code>? </p>
  
  <p>Note that the element may also have another class, which I am not selecting for.</p>
  
  <pre><code>&lt;div id = "my_id"&gt;
      &lt;span class = "my_class hidden"&gt;hi&lt;/span&gt;
      &lt;span class = "my_class"&gt;hello&lt;/span&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>was trying</p>
  
  <pre><code>$("#my_id [class*=my_class ]")
  </code></pre>