The most effective way to greatly reduce substance abuse in teenagers would be to get them out of the artificial social environment of schools in which they're mostly surrounded by people of the same/similar ages. Real life is not like that. Homeschool using parent-selected social learning groups. Organize learning centers that offer parents and students choices tailored to their academic levels and interests: https://medium.com/non-violence/stakeholder-control-democratizing-primary-secondary-education-576d47cd8d23