"The Substitute" is not high art. Ebert reviewed it as a serious film and gave it a very negative review. But as a B-movie where the teachers get revenge, the bad guy dope-peddling punks and principal get their due, it is a virtual "The Patriot" for the high school system. You can't help but smile and root and rejoice when punk after punk gets thrown out the upper floor window by Beringer while the principal relaxes in his office, assuming the punks will prevail.
Beringer plays a mercenary who becomes the substitute when the real teacher is injured by the punks. With his background in covert operations, and his support network, the punks are no match for him. I've seen it several times on network TV, its one of those films I just can't stop watching. Roy Frumkes, who wrote each of the "Substitute" movies wasn't trying to create a classic, just fun entertainment. In a personal communication he said, " Not only did that film surprise everyone by doing as well as it did, but when it came time for the three sequels, my contract was worded so that they couldn't get rid of me!" Thus providing his retirement fund. Hey! Some people win the lottery. His was a different kind of lottery.
I like "The Substitute" a lot. I think Roy Frumkes is a classy guy. It is destined to be one of those cult films that lasts much longer than logic says it should.
Edit AUG 2023: Watching it yet again after 21 years it occurs to me it also hits hard on two issues - fighting drug trafficking and encouraging students to pursue a good education instead of becoming a member of a gang.