Uhhh, oops. Looks like everyone had covered this already, but Toby still raised his hand to contribute, sort of waving it around as he did.

"A potion is something with magical effects that you brew, by adding things to a cauldron and heating it or cooling it and stirring it in very very specific ways." Sure, let's go with that. Not what the texbook said but Toby wasn't one for remembering things verbatim. He was just sort of winging it here, being much better at the practical portions and knowing about ingredients and everything.