I might be unusual, but I can only remember one incident that was definitely sexual throughout my time at such a school. Of course, it might be that any sexual behaviour was entirely suppressed in public, but I cannot believe this to be the case. I am discounting the usual kiss-chasing and perhaps skirt flipping, which might be seen as sexual. The incident I witnessed in the playground, just metres away, involved two boys in the final year, so about age 11, who were clasped together, grinding away, obviously sexually aroused, and masturbating together quite openly. I recognised it as such since I had been masturbating for perhaps a year or so, but in private.
What did you experience or see in the behaviours of others of a similar nature whilst at such schools?
Secondary school was a different matter entirely.
Don't be shy.