Right then.  So long as he's asking things anyways:  Is using direct Prestidigitation for all of his wall-writing purposes, in fact the sort of thing that trains his magical abilities at all.  Keltham just started doing that at one point, but then every time he did it, he was in the middle of class and it was the wrong time to stop and ask questions of Carissa about that, and at other times, he wasn't remembering to ask.

So long as he's asking things anyways:  Is using direct Prestidigitation for all of his wall-writing purposes, in fact the sort of thing that trains his magical abilities at all.  Keltham just started doing that at one point, but then every time he did it, he was in the middle of class and it was the wrong time to stop and ask questions of Carissa about that, and at other times, he wasn't remembering to ask.