I think Smithers picked me because of my motivational skills. Everyone always says they have to work a lot harder when I’m around.— Homer
One of the staples of the Simpsons' opening credits is the blackboard gag. Bart writes something on the chalkboard as a punishment, quite often ironic. Here we list them all, including screenshots where useful. Any episodes not listed here do not have blackboard gags.
Season 12 starts 27th September.