"Last Week Tonight" is on hiatus, but host John Oliver made a brief return to wish students off on another school year. The online exclusive clip titled "Back to School" prepared students for what they'll learn in the year ahead in classes like biology, chemistry and math. Oliver goes through each subject and gets honest about what students really needed to know.

For American History, Oliver advised students to do some independent research on one topic, Warren G. Harding's love life. "The only thing you need to learn about American History is something that they are almost definitely not going to teach you, and that is Warren G. Harding's love life, which, believe me, was spectacular," Oliver joked, reported Rolling Stone "Seriously, Google 'Warren G. Harding penis named Jerry' right now, and you will not be disappointed."

"Although to do that, you may have to switch SafeSearch off." As for World History, despite its name, Oliver said students likely won't learn much about Asia and Africa. "You will leave school knowing as much about those two continents as I do about actor Penn Badgley," Oliver said, according to Entertainment Weekly.

However, Oliver argued that the most unnecessary subject of all those required was math. "You're going to be repeatedly told 'You're gonna need this when you grow up.' That is bullshit. You will need addition, subtraction, multiplication and division," Oliver says. "I'm an adult with a job and I cannot remember if a logarithm is some kind of exponent, Kenny Loggins' first album or a method of lumberjack birth control, I don't know. So ignore it. Just ignore it."

Check out the entire "Back to School" segmant from "Last Week Tonight" below!