Stuff like this is still happening. I graduated high school in 2012. During our final semester, my friend decided to try logging in to the school router. He thought it would be passworded, but it was completely open. He shared this info with me and a couple other friends.
We had fun for a bit restarting the router when we wanted to mess with a boring teacher, but eventually one of them set a password, the school IT guy found himself locked out, and I found myself getting threatened with expulsion. The principal interrogated me and asked if I knew what port scanning was, and even accused me of lying when I said I didn't (I really didn't!). I told him as much as I knew - which wasn't much - because I didn't want to get expelled a few months before graduating.
Long story short, the friend that set the password got expelled, the one that found the vulnerability got suspended for a week, and everyone else got off scot-free. I heard a year or two later they started offering programming classes there.