For a short commute to school, ride whatever is comfortable. Gearing may be important if you've got hills or wind to contend with, or if you're not in very good fitness.
Most importantly, don't spend too much on a campus bike, and don't get one that looks too flashy. Get two quality (Kryptonite) locks...U-lock and cable lock...and know how to use them. School campuses are known for bike theives.
