If you have classes all day and minimal time to eat, make sure to bring food along with you for the day. These snacks ideas are delicious and nutritious and will fit nicely in your backpack:
Rice Cakes with Nut Butter
Veggies and Hummus
Tuna Packets with Spinach and Mustard
Apples and Nut Butter
Trailmix of Nuts, Dried Fruit, and Dark Chocolate
Hard Boiled Eggs
All these snacks have a balanced mix of carbs, fats and proteins. They will keep you full and alert for a full day of classes.