Actually, it was alot like a normal high school, except there was way more of a push on the sciences than most (that and the average student GPA was higher, so not everyone was a 'genius' per se, but performed at a higher than average level). There was quite a bit of variety in activities like in other schools as well.
Not everyone was a mathlete or scientist or whatever though, it was mainly those who wished to pursue a career in that particular path and met a certain grade level for the specific subjects (was a mathlete myself lol).
Honestly, Peter being in a specialized school isn't a problem (trust me, it's not filled with a bunch of budding science genius type characters as one would imagine, besides higher than normal grade requirements and heavy STEM emphasis it's pretty much like a normal high school). Heck, the fact that he's at one on a scholarship could be a point in which his double life messes with his academic career (since he's on a scholarship, he'd obviously have to meet a certain grade requirement and being Spider-Man could mess with his grades). There's a variety of student types and different activities/clubs available, at least for my school and a couple of others in my hometown.