This doesn't make much sense. The other day I saw the first episode of Happy Days, and Richie says he's a junior. Then the Next year they are Supposevley Juniors again. And then in the 3rd season theyr'e Juniors once again. Finally they where Seniors in Season 4 and they graduated. It's funny because in the first episode Potsie tells Mary Lou Milligan Richie was left back 3 times, and it turns out, eventually they all where. I heard they did the same thing on Welcome Back Kotter.

Gee,that is WEIRD,I don't think even Lenny and Squiggy were
held back THAT long.It just could be their teachers wanted to
get rid of the L&S gang a whole lot faster than the HD gang!!!!:)
btw:Interesting piece of HD/L&S trivia,the HD and L&S gangs
went to rival high schools.Richie and company went to Jefferson
and Laverne and Shirley and gang went to Jefferson's crosstown
rival Fillmore.:)