You got dressed in your gym suit, yes, they called them gym suits because for girls anyway, they were often one piece snap up, ugly as sin, outfits. Then you had class, did drills for whatever sport was in season, maybe played a game, then went back to the lockerroom and were forced to take a shower. The teacher always stood at the shower exit with clipboard in hand, checking off each person as she came out. Most of the time these showers were group affairs. No private shower areas.
Most of us hated this business of having to shower as a group. Most high school students, especially girls, never felt comfortable in a mass shower. My high school's gym shower was an L shaped one which you walked through with shower heads on either side wetting you down as you waded single file behind and in front of other members of the class. Good grief this brings back awful memories I thought I'd sublimated forever.
Anyhow, it seems showering en masse is still going on in modern day physical education classes and students still don't like it and some are refusing. They think it's way too weird and prefer to wait until they get home.
It is way too weird, always has been. We never spent much time drying off, just wanted to get dressed as fast as we could which meant spending the next class period still damp.