Does his teacher know his background? Can his teacher tell the class as a whole that she's had this wonderful idea, that an alternate assignment will be for the kids to chart the *next* 10 years of what they hope for, instead of the last 10 years? Perhaps other kids would choose that option also, but at least your son, instead of having to reveal his history when he's trying to make friends and not be "different," could just seem to have chosen the second assignment option.
Hugs to you. At least with "bring your mom/dad to breakfast" days, the schools are getting pretty good about saying "or someone else who's special to you." In this case, it seems that the teacher is expecting that everyone has had a rosy 10 years--but you know, since probably not 100% of the class is excited about this project, I bet Assignment Choice #2 would have a few takers, not just your son, so he wouldn't be alone.
If you're afraid of butter, use cream. ~~ Julia Child
As you cook, you enjoy omniscience about food that no amount of label reading can match. Having retaken control of the meal from the food scientists, you know exactly what is in it. (Unless you start w/cream of mushroom soup, in which case all bets are off.) To reclaim control over one's food, to take it back from industry & science, is no small thing; indeed, in our time, cooking from scratch qualifies as subversive. ~~ Michael Pollan