Have you tried EndlessOS ? I haven't, but I would be curious to know what people involved with education think. It is probably better suited for places which don't have good internet, but that aside, I still think it looks promising. I saw their promo video (https://www.youtube.com/watch?v=vgUzdb3S2uA), and it has that vibe that Ubuntu originally had when they were new (with the whole linux for human beings thing and free CDs). It also has some new ideas regarding package management with ostree + flatpak.