Bill & Ted's Excellent Adventure (1989)

Bill (Alex Winter) and Ted (Keanu Reeves) are high school buddies starting a band. However, they are about to fail their history class, which means Ted would be sent to military school. They receive help from Rufus (George Carlin), a traveler from a future where their band is the foundation for a perfect society. With the use of Rufus' time machine, Bill and Ted travel to various points in history, returning with important figures to help them complete their final history presentation.