Somehow, Sam managed to calm the teen down. By the time police came, Sam had everything under control. Technically, Sam is an ESP, or educational support personnel. The teachers will tell you what your child is learning. But it's the ESPs who will tell you what your child is doing.
Liaisons often make sure a child is fed and has warm clothes.
They check on children who are left to make their own way to school and don't get there. Or to buy someone a pair of tennis shoes for gym class. Or track down a parent who doesn't have a phone but needs to pick up a feverish child. Actually, that barely scratches the surface. I believe all schools should have them.