I approached his teacher, and she was really awesome about it- I have 30 minutes to do my thang on October 12th. And because I am a teacher-nerd, I have my lesson plan already written up and ready to share with you :) It is geared for K, but you could easily do with with up to third without tweaking it, and just add more of the science-y stuff and possibly a different book for older kids.
I also have a handout for the kids to bring home to their parents...It is kind of like a mini Ben book (the one I am using for the presentation), but I am putting Chase's photos in and filling it in with Chase-specific words.
*Disclaimer: I did NOT think up any of these activities myself...they are borrowed from a presentation from the Down Syndrome Guild of Greater Kansas City. I just put them all together. :) Borrowing ideas is what I do best!