Last week, actress Marcia Wallace—well known as the voice of Springfield Elementary teacher Ms. Krabappel on The Simpsons—passed away from complications related to breast cancer at the age of 70. This weekend, the show paid its own unique tribute. After airing a classic episode involving her character from 1992, Fox premiered a new episode of the animated series that opened with a very special opening credits chalkboard gag (as seen below). We’ll really miss you Mrs. K. …