I am currently reading Learning jQuery Third Edition - Chaffer, Swedberg and even after reading Chapter 3: Handling Events - I am unable to solve question #three which is very frustrating!

I am trying to figure out how to using jQuery's toggle() or toggleClass() Method along with passing an event through a click function to make the chapter text hide and visible. Can anyone help me with this problem? Thanks in advance.

Here is the question.
3.) When a chapter title (<h3 class="chapter-title">) is double-clicked,
toggle the visibility of the chapter text.

HTML code:
        .hidden {display:none;}
    	.hover {cursor: pointer; background-color: #afa;}

<div id="header">
        <h2>A Christmas Carol</h2>
        <h2 class="subtitle">In Prose, Being a Ghost Story of Christmas</h2>
        <div class="author">by Charles Dickens</div>

      <div class="chapter" id="chapter-preface">
        <h3 class="chapter-title">Preface</h3>
        <p>I HAVE endeavoured in this Ghostly little book, to raise the Ghost of an Idea, which shall not put my readers out of humour with themselves, with each other, with the season, or with me.  May it haunt their houses pleasantly, and no one wish to lay it.</p>
        <p>Their faithful Friend and Servant,</p>
        <p>C. D.</p>
        <p>December, 1843.</p>

      <div class="chapter" id="chapter-1">
        <h3 class="chapter-title">Stave I: Marley's Ghost</h3>
        <p>MARLEY was dead: to begin with. There is no doubt whatever about that. The register of his burial was signed by the clergyman, the clerk, the undertaker, and the chief mourner. Scrooge signed it: and Scrooge's name was good upon 'Change, for anything he chose to put his hand to. Old Marley was as dead as a door-nail.</p>

my jQuery code (not working):

        		$(".chapter-title h3").click(function(){
        			$('.chapter-title p').toggle('hidden');
			});// end