Terry sighed as the House Elf told him what had happened, even as he pulled on a robe and headed down to the grounds. He'd been extremely explicit in telling the students they were not to practice the color change charms on anything other than inanimate objects until the next class.
"Sorry about this Mr. Lawson," he said, as he fixed the guilty students with a glare. He took points from each of them, and assigned a foot long essay on the dangers of performing unknown charms on animals, or people.
But, since the opportunity had presented itself, he made them show him exactly what they'd done, and then walked them through turning the dog back to his normal shade. Once that was done he said, "I want those essays by Tuesday," and the kids took off, hopefully in the direction of the library.
He waited until he was sure they were far gone, and then smirked at Craig. "So, I take it you're not a fan of blue dogs?"