Chocolate sounds good - but maybe it should be left at home - it could smear on things.
Bottled water - I think I would avoid any liquids that are colored - in case they spilled. I would feel bad if it landed on my stuff - terrible if it landed on someone else's things.
Maybe non-sticky snacks? Or wrapped hard candies?
I appreciate a listing from the teacher.
I also appreciate a detailed list of what "the usual sewing supplies" are.