Bart's rebellious attitude has made him a disruptive student at Springfield Elementary School, where Bart is an underachiever and proud of it. He is constantly at odds with his teacher Ms. Krabappel, Principal Skinner, and occasionally Groundskeeper Willie. Bart does poorly in school and is well aware of it, having once declared, "I am dumb, okay? Dumb as a post! Think I'm happy about it?" On one occasion, Lisa successfully proves that Bart is dumber than a hamster, although Bart ultimately outsmarts her in the end. Bart's thoughts are often illogical― he once thought if he died and reincarnated as a butterfly, he would be able to burn the school down without being suspected, thinking that he would be able to hold a gas can as a butterfly. He has also thought if he wrote his name in wet cement, people who see it after it dries will wonder how he managed to write his name in solid cement. In "Separate Vocations" (season three, 1992) Bart becomes hall monitor and his grades go up, suggesting that he struggles mainly because he does not pay attention, not because he is stupid. This idea is reinforced in "Brother's Little Helper", (season eleven, 1999) in which it is revealed that Bart suffers from attention deficit disorder. His lack of smarts can also be attributed to the hereditary "Simpson Gene", which affects the intelligence of most male members of the Simpson family. Although he gets into endless trouble and can be sadistic, shallow and selfish, Bart also exhibits many qualities of high integrity. He has, on a few occasions, helped Principal Skinner and Mrs. Krabappel: In "Sweet Seymour Skinner's Baadasssss Song" (season five, 1994), Bart accidentally got Skinner fired and befriended him outside the school environment. Bart missed having Skinner as an adversary and got him rehired, knowing that this would mean that the two could no longer be friends.