They do a drug and alcohol survey in our district among middle and high school. I don't know if it asks about sex because I have never let my child take it. Interestingly, they do not ask for permission slips; it is up to the parent to send in a no-go document. The questions are available but you do have to request them. What irks me, is the info is handed over to an outside psychologist at a university who is doing "research." My child is NOT a free research subject.
It does sound as if they notified the parents and they didn't bother to dig into it. NEVER trust schools. Do your homework and I include my child's former private school in that.