Before my 10-15 mile ride I eat yogurt with granola cereal in it and a hard boiled egg. When I get to work I eat oatmeal with raisins and cinamon -- easy to store and prepare.

Since you are in school, if you don't have a way to store things, you might be able to carry something microwaveable to eat once you get there. I guess if I were you I'd put a serving of oatmeal with the raisins and cinamon in a ziplock bag and take it. That would be very light and not take up much real estate. Maybe you'd need a container if there isn't something to use at school. Either way, add hot water and enjoy.

Bananas and apples are easy to carry and deal with too.