These busybodies start with the assumption that every teen pregnancy is accidental. That is not the case. They always make the case that making birth control available will prevent every teen pregnancy. But as long as there is a voluntary component that required the kids to use the birth control being offered, most of these pregnancies are still going to occur.
Of course pregnancies will continue. Kids don't take any pill with regularity,if at all. They think they are immune to conceiving kids. Maybe the teachers are trying to protect themselves, 'if you know what I mean'? /sarcasm