Covenant Eyes is a reliable software to help protect your kids and their electronic devices. The stats are staggering with 73% of teens watching pornography and the average age of initial exposure being 12. So the question is less about whether your kid has been exposed, but rather if not, then when. Equipping your students with a resource like Covenant Eyes could go a long way.
Companies like Protect Young Eyes might be another good resource. Their job is to walk alongside parents and train them in how they should incorporate technology into their kids' life at a pace that will set them up for success.