I’ll keep it short and sweet: Family. Religion. Friendship. These are the three demons you must slay if you wish to succeed in business.— Burns
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.