A petition would be a nice instrument, a good start. Concerned parents can start this on a school by school basis (i.e. for their own schools). At a later stage - and to have broader impact - we could have this at the CHT level.
Like, say, a petition website with a couple hundred thousand signatures (the more the better, of course) would add a lot of weight and awareness. The petition could ask for schools to adhere to a covenant drawn up by CHT and offer a program / checklists to implement good policy.
You will probably get schools to be willing to be on all sides on the scale… ranging from zero tech to full tech. For all of these there are best-practices to be found. We could provide certifications, rating system and a logo program, similar to this discussion for apps and websites: Humane Technology Certification project