This is one of those vague memories that nag at me, but I've lost most of the details over the years. I saw in on TV somewhere in the 1990s in the United States (Ashland, KY if that's relevant). It would have likely been on broadcast TV as my parents were late adopters of cable TV. A new teacher arrives at a school. She's a free spirit, inspiring the children and annoying the administration, and there was a hint that she employed some sort of magic. Near the end, things come to a head with the administration, and the students stand up for the teacher (something involving painting a mural of a mythological creature, maybe a dragon or a griffin). They go to the classroom to tell her about it and she's gone, I think leaving a note for the students in a drawer.
I have this vague memory of the word "witchcraft" being used to describe something she'd done, but I'm not certain. I remember I was rattling off a series of magic types from David Edding's The Belgariad to which my mother reminded me that another name for magic was "deviltry" (my mother was never big on the idea of people claiming magic in the real world, feeling that it was likely the Devil trying to tempt people away from God).
I'm 90% certain it was an actual TV Movie, not a cinematic one shown on TV as a rerun. It had that style associated with broadcast TV (something to do with the type of film and camera used, I'm told).