Here is a few shots of my k/1 classroom setup. We are currently studying the life cycle of the the frog. Right now the tank contains some tadpoles, guppys, snails, and two very small fancy goldfish.
I've got a little 12 gallon in my (4th grade) classroom. It's got 2 baby albino senegals, a dwarf gourami and 4 <1" tetras ... and some driftwood and flowting plants.