[@Obscurus] I'd imagine it would begin with the Professor's dividing the kids up depending on what their power consists of (E.G Someone practicing Atmokinesis wouldn't be practicing with someone practicing with mind manipulation.), and then just telling them to... go wild? I guess?
Maybe after the students have pretty much got a good grasp of their power and what it can do, they'd work on building their strength/tolerance up, and get pitted against one another despite what their power is to see how it would work in a real life situation.

I guess, that's how I'd do it anyways.