Oh... what was that smell? Daxton had not moved very far from the door upon taking a seat, and likely still had the benefit of the air from outside the classroom for at least a few seconds while everyone walked in. But suddenly there was a great waft of stench, and Daxton gagged, before breaking into a none too pleasant coughing fit. Was that thing here? The one with the poisonous perfume? The new Divination teacher and potential hag? There was no time to look; Daxton was busy using his space blanket to hold over his mouth and nose before the odour of the room made him throw up.
Then Airey Flamsteed was right there, and Daxton gave him an accusatory look. That smell, was it him? Did he bring it over here? Because if so, he needed to leave.
Wait, what... oh... the...
Daxton frowned, though with his face half-hidden, all that was visible was a subtle furrowing of the brow as he looked back up at Airey Flamsteed, trying and failing to gauge the man's expression. He had come over here, addressing Daxton (by name), because his name plaque had not been right. But if he already knew his name - and had just proven the fact - then why was it necessary? Answer: it was not. But it was a rare opportunity for fun.
Now manoeuvring around the space blanket he kept over his mouth and nose (and quite uncomfortably warm it was getting under there too), Daxton reached across to turn the parchment over, then wrote something new on the other side. A tap of his wand, and he had a new plaque.
He did not bother to answer the question put to the class, partly because he was only just getting around to retrieving his notebook from his bag, and partly because the only answer he had in mind was that Astronomy, the universe in general, was interesting. Not the
boring kind of interesting, things people claimed were interesting and fun but were probably just lying, but the
overwhelming kind of interesting. There was always something else to learn from the universe; it was limitless, there always was the opportunity to discover something that nobody else had discovered, if enough time was devoted to studying it. And aside from all that, as someone who felt as though he was not human in anything other than appearance, studying the universe and anything that was not Earth was the closest Daxton ever felt to being home.
As for why it was a compulsory subject, adults just liked telling children what to do, and what to study. It was as simple as that.