That looks good for power levels on the surface. What do the advanced setting look like? How do the rest of them look, similar? Are your 2.4 radios turned on for every access point or have you limited that down?
I'm assuming your classrooms are pretty normal sized so even if your AP placement isn't perfect, given the amount of AP's you have, it sounds like there is a lot of flexibility to tune your radios the way you want them to.
Back to your cell size question: Given that you have an AP in the halls and in every classroom, you want to get it as small as you possibly can. You most likely have a lot of bleed-over into adjacent rooms.