“Welcome Back Kotter” was a funny sitcom about a teacher who goes back to his neighborhood where he grew up to teach in his old high school. He teaches a class of misfits called “Sweathogs” (from which TV.com level 2 gets its name). Each of the characters came from the stand up comedy routine of comedian Gabe Kaplan, who stars as the teacher, Gabe Kotter.
Some of the people in the show have disappeared with the sands of time. The most notable non-disappeared actor is John Travolta. If you get a chance to see this series, watch it. It is very funny and you will be amused to see the young long haired Travolta.