I didn't originally plan for Kevin to have a reaction to this, but once I got to the subject of trades, it became retroactively obvious as all heck that Kevin would have a personal interest in it.
Kevin's a character who was here because, logically, he had to be if Ashley was going to be here. Ashley doesn't tend to hang out with Tedd alone unless practicing magic, and that means mandatory presence of Kevin was mandatory.
Kevin didn't have to stick around, however, and it actually made sense for him not to if Ashley was going to get distracted from practice. If Kevin isn't educating, Kevin is sleeping, and that's how Kevin likes it.
Now, however, there is something Kevin should know as a teacher of introductory magic that he doesn't, and suddenly Kevin has a horse in this race no matter how derailed his lesson with Ashley gets.
Not that that's a BAD thing. I just hope people like Kevin, because he's definitely going to want to learn more, and update his curriculum.