Hollowed out Bell peppers (different colors) fill with your favorite dips, sereve with some wild flavored chips or crackers or just cut vegetables.
fruit kabobs
bagle bites or pizza rolls (these are still good at room temp)
little smokies wrapped in a bit of canned biscuit or crescent roll (each biscuit or crescent roll can be cut in 3rds)
Make pitchers of smoothies pre-fill plastic cups in the colors of the highschool, use colored straws....... take a tray of cups out but keep the rest refrigerated.
Brownie bites or mini cupcakes (frost with vanilla frosting, use the "spray color" in HS colors