looking for Squarespace jquery examples

I am having a devil of a time trying to get jquery to work on my Squarespace site. I can use page header injection to run regular JavaScript, but I can't even make the most simple jquery work.

Does anyone have a Squarespace site with working jquery they can point me to so I can see what I'm doing wrong? Or can someone post a very simple Hello World using jquery?

In case it helps, this is what I have in my page injection:

<script src="//ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<script type="text/javascript">
  $(document).ready( function() {
  $("p").text("The DOM is now loaded and can be manipulated.");
  $('.summary-title').append('<p>Test</p>');
}
</script>