This short film is perfect in a film class, but it also works well in any class dealing with a theme of decision-making. Film, discussion, and quiz can be done in less than two class periods. The film itself was an Academy Award Nominee for best short film. You might have to search for it online or at the local library, but it's worth the effort if a time-travel take on those big decisions in life might work with your themes in class.
After you find the film and decide it might work, a buck for a 10-question quiz is well-worth the advice I gave you to use the film in the first place, even if you were predestined to do so even without my advice in each alternate universe.
This film also makes science (fiction) seem a bit cooler than some of us might think, so it's a nice little short for science class, too, especially if you're talking about the science behind time travel.