Two, but don't ask me how they got in there.
EOM
Only 2, but I have no idea how you're gonna fit both of them inside a lightbulb.
Only 1, but it takes them 15 episodes to do it.
None. Anything not completed during the lesson is added to the homework.
Well it pizza heck out of me.
TL;DR
When its head is up a Fairy's skirt, then it's a goblin.