You've done some good things with the QA markup. 
* You've kept it consistent
* You marked up the Qs different than the As

Overall, you want to accomplish a few things with the markup of the questions and answers:
 
1. show that the question and answer are a pair (related elements).
2. Have something be different between the two so that you can style the questions differently than the answers.
3. Use semantic markup as much as possible.

I should say up front that there is no perfect answer for how to mark up this assignment &mdash; see [this discussion](http://www.sitepoint.com/forums/showthread.php?695009-Appropriate-Markup-for-a-Question-and-Answer-List). There is no Q&A element in HTML5. So I'm more looking that you have made an effort to do the three things above.

You have 2 and 3, you just need something for 1 showing they're a pair. You can use a grouping element like a section or div to do that:

````
<div class="QA">
    <h3>question</h3>
    <p>answer</p>
</div>
<div class="QA">
    <h3>question 2</h3>
    <p>answer 2</p>
</div>
````
or

````
<section class="QA">
    <h3>question</h3>
    <p>answer</p>
</section>
<section class="QA">
    <h3>question 2</h3>
    <p>answer 2</p>
</section>
````