Try trail mix, peanuts, walnuts, soynuts, raisins, sunflower seeds, dried fruit, ect., bars, tuna or chicken cut up in a tupperware cntainer with relish or mustard, shakes. I went through the same thing last semester and these are the things I brought to class with me. One professor was a real bitch and wouldn't let us eat anything or drink and it was a 3 hour class. But I talked to her and told her what I did and she let me have my shakes.