The Chromebook 'powerwash' seems to fulfill this requirement nicely[1] - you can even let students drop the machine into Developer mode, play with Crouton[2] and so on, and if (when) things go wrong, poof, a single chord at startup and you're back. 1: https://support.google.com/chromebook/answer/183084?hl=en 2: https://github.com/dnschneid/crouton