Here are a couple of links for helping you start thinking about your personal essay.  Yes, these both say "college application essay," but they are still applicable to essays that are reflective, personal responses to the prompts provided.  And if you ARE going to be submitting one of the Common App choices on an real application, then I think the first reference is a very useful starting point:

http://collegeapps.about.com/od/essays/a/common-application-essay-prompts.htm

http://in.princetonreview.com/in/2013/07/dissecting-the-new-common-app-essay-prompts.html

This one has a questionable video attached, but do look at it for the overall advice about waiving your right to see letters of recommendation.  I'm not sure I heard the counselors mention that this year, and it's still important advice.
http://www.huffingtonpost.com/patrick-oconnor/common-application-coming_b_3671475.html

Here is the link to the formal essay assignment given out in class on Friday:

Senior Personal Essay 2013

The first draft of this assignment is due, typed according to the specific instructions on the hand-out, on Monday, Sept. 30.  There will be a peer-response that day, which will be a valuable step in the process of developing a compelling, effective, and well-written essay.