Gotham High (cancelled Batman animated series; 2009)
Gotham High was the concept behind an animated TV show about a teenage Bruce Wayne attending high school with his future enemies and allies.
When creator Jeffrey Thomas drew a picture of a young Joker and Harley, DC liked it enough to order an entire series based on the concept.
The plot would have Bruce Wayne attend High School with Barbara Gordon and his entire Rogues Gallery. Each character would have represented a social clique (The Riddler was a nerd, Killer Croc was a bully, Mr. Freeze was the "cool" kid, etc.).
The series was cancelled for reasons unknown.
It is possible that elements of the show were reworked into the web series DC Superhero Girls which also involved teenage versions of DC characters attending high school. This show also featured characters from the Batman franchise.