the pilot episode? The toning down of all those characters after that very first episode. I found out that the refusal to air the show in boston led to the toning down. The Pllot was my favorite episode and number 2 is when the Art Teacher was in love with Mr. Kotter

That, my friend, was a necessary evil of tv at the time...there was no way that the networks would let a multi-ethnic group of seemily dangerous street punks into the living rooms of America without there being a firestorm of controversy. Thus the transformation of the Sweathogs from semi-real problem kids into an ersatz Marx Brothers, with Gabe as Groucho...(of course, if this show was made today, it would treat the kid's problems...and Mr. Kotter's solutions...with an oppressively heavy hand.)

In hindsight, it was probably better that the Sweathogs were "lightened up", as it were...they never really lost their audience identification, and that's why the show is still so fondly remembered today.