What is the simpsons season 17 episode 21?

The Simpsons Season 17 Episode 21 is titled "The Monkey Suit." It first aired on May 14, 2006.

In this episode, Ned Flanders becomes the new principal of Springfield Elementary school and immediately enforces a strict creationist curriculum. Lisa becomes outraged and takes the issue to court to fight for the teaching of evolution in schools. During the court case, Marge decides to teach her family about evolution, leading to a rift between Homer and the rest of the family.

"The Monkey Suit" addresses the debate between creationism and evolution in schools and also satirizes those who challenge evolution in favor of religious beliefs. The episode received positive reviews and was praised for its handling of a controversial topic in a humorous and thoughtful way.