The Doctor had arrived earlier that day. Maybe it was because he was certain that he had accidentally released some sort of small alien insect from inside the TARDIS into his classroom and he wanted to catch it! Maybe it was because he needed to set up some form of strange physical representation of Black Hole dynamics in shifting gravity pockets? Well actually it was a bit of both... The two things were oddly connected. The insect was capable of shifting gravity around itself in a small pocket, but that also made it very difficult to keep a hold of. The Doctor was certain it was somewhere under his desk, judging from the floating inkwell by his feet. And so he had spent the better part of a half hour just trying to contain the insect and when he finally had it back in its stasis jar, he peeked his head out from the desk to see his students had arrived. Not just his students. Rose was there too wearing a very familiar brown longcoat.
"Ah.... is it that time already?" he asked, standing up, clumsily opening a drawer as he did so to cram the stasis jar inside for later. "Hello, Rose!" he grinned, waving at her like an idiot. If there was anything that made him seem like an old man out of touch with the world, it was moments like these.
"Right!" he said loudly, clapping his hands together. "Where was I last time?" he asked as he spun on his heel to look at the wall sized blackboard, covered in scrawls and equations from the previous lecture. "Gravity" he said with a big grin.