The teacher of Bart Simpson's class at Springfield Elementary is Mrs. Krabappel, also known as Edna Krabappel. However, it's worth mentioning that the character of Edna Krabappel was retired from the show "The Simpsons" after the voice actress who portrayed her, Marcia Wallace, passed away in 2013. Since then, the show has had various substitute teachers and has not introduced a permanent replacement for Mrs. Krabappel.