Ag school

"I can't beat you in an argument, Leia. I'm no politician, and the ag school in Anchorhead didn't have a debate team."

- Luke Skywalker

An ag school was a type of educational institution. There was an ag school in Anchorhead on Tatooine. Luke Skywalker presumably attended the ag school there.

Appearances

 * Luke Skywalker and the Shadows of Mindor

Behind the scenes
"Ag school" is a common abbreviation for "agriculture school" in the real world, and since the human on Tatooine were mostly moisture farmers, it is likely that this is the case in the Star Wars universe as well, though it is not explicitly stated.