I was mainly aiming for current teachers having to deal with her apparent disinterest in some of her classes, but yes, previous teachers are good too! Celia would be more than open to continued contact with her old teachers after her elementary years, particularly if she liked them, and Ain certainly sounds like the sort that Celia would eventually see more like a friend after awhile.

Celia's favorite things to do back in the day would have been obviously any sort of outdoor stuff (feel free to assume her parents were called any number of times about her wandering around), plus hands-on stuff like art/science projects, and reading (mostly fantasy stuff), so she'd have done best in relevant subjects with everything else lagging behind somewhat. She also takes a huge interest in anything her friends are doing, so she'd have done particularly well with group projects if Ain made sure she was working with someone she knew.

She probably also doodled in her notes a lot and had to be reminded to pay attention at times, but Ain could probably have figured out a way to keep things interesting for her. I'd forgotten to note in my toplevel comment that Celia is very much interested in things that feel new, which is a big reason for the whole wanders off thing; she mostly wants to see/do things she hasn't seen/done before.