So exciting to see all of the pictures on social media of project weeks and winterims. For current students, have you participated in one, and what have you done? Which schools have this opportunity?
Schools I know with Project Weeks and Winterims include:
Lawrence Academy
Kimball Union
Forman
Proctor
Winchendon
Berkshire
Suffield
Pomfret (2 1/2 weeks between Thanksgiving and Christmas !)
I know Kent does. They have almost all of March off so run some service trips then for a week of the break. They also have them after school lets out. I read that they have a group now where students can do community service as a semester long activity too. I feel these are all valuable experiences.
SPS has service-learning off-campus programs during Spring Break. (Kid is on a service trip with Habitat for Humanity right now. We expect she can fix our roof when she comes home! 
) Students can also choose a semester of community service in lieu of athletics.
Brooks