"Homework," he admitted immediately, rather hoping it would explain why he'd come down here in such a hurry. He'd been bored and sick to death of Potions, that was all. "All seems kind of stupid, now, really. I know it's important," he continued, with a valiant effort to suppress a preemptive eye-roll. "But every time Slughorn gives us another twelve inches, I want to throw him in the lake."