I used the PPMD "Teacher's Guide to Duchenne's Muscular Dystrophy" and the accompanying classroom DVD. The DVD is very helpful as it simplistically explains what is going on in a child like fashion.
We do it every year for Harrison's class. If Sam is starting to fall or require assistance - in my opinion it is right to have the talk now. It seems the earlier his classmates are exposed to it - the better.
I find early in the school year is the best. Set's things off on a positive note. Before issues arise. You can order the materials from PPMD. Just email Ryan.
Hugs, Jeanette RN, MSN, CCRN