Hey Allison,
I think one of the Delta Zeta's had this exact same problem (talking to high school students about the benefits of Greek Life) I forgot which forum it was posted in. So you might want to check the Delta Zeta forum and also the Greek Life forum and maybe this forum to see if you can the thread. The thread gots some pretty good responses to.
Good Luck with your talk!
p.s. Email me when you get a chance