Actually, it kind of sounds like they don't have the biggie tank, so it's a semi-display, semi-quaranteen. For a class room that actually makes a bit of sense on some levels.
What I'd do, especially if it's a class project, is go ahead and set it up as a "FOWLR
", get the live rock (10 to 15 lbs) and cycle it. Gives you a chance to explaine the process to the class (And some basic organic chemistry depending on their age group. And in spite of the general disdane with which they are held, letting younger kids do a test strip (I'd double check readings myself) could make them feel engaged.
Get yourself a Occ. clown (might get away with a pair. Or a fire fish too. Love those little guys) or something else that could do okay in a ten (Some would debate if anything can, but we're talking about a nano-tank here). Then the tank is going, and when you get a bigger tank, you can transfer just about everything over (Might need a bigger heater. Depending on tank you might just transfer filter and then not be overly worried about a cyle. Also would then need less new live rock) Whatever livestock you get, you want hardy.
Keep in mind, with a ten you're going to have to watch the water like a hawk. I've got a five I've managed, finally, to balance, so it's not like it can't be done.