11th and 12th graders are children. Nothing is more childlike than for them to try to act lke adults.

They / we want so badly to be adults at that age that we do adult things - usually without understanding or appreciating the consequences. Hopefully teachers let us explore a little but also remind us firmly that we are not adults and will be able to look back to see how childlike we still are in a few years.

Any teacher or parent treating 11th or 12th graders as adults is just holding their breath hoping the kids won't screw up too badly before they finish growing up.