When I was in high school (maybe age 14) I worked on the school play, doing the lights. Consquently I had a key to some of the back areas of the stage. One was a really weird place with no lights. I opened the door and climbed up a ladder with a flashlight. It seemed logical that it was behind the girls change room. I crawled over some heating ducts to a wall and pushed a screwdriver thru the drywall (it was only on the other side-this side just had the studs exposed).
Bingo-a view into the girls change room. It took a while, but I eventually figured out the schedules for most of the girls gym classes. I made sure I could cut my classes and go up there and masturbate for hours. It was GREAT!!! I got to see all the girls in their panties and bras and most totally naked: from the small, grade 8's to the more mature grade 12 girls. I must have unloaded a gallon of cum in that area! Oh, I miss high school, and the school is still standing.