This intro song to The Big Bang Theory covers topics such as the origins of the universe, universal expansion, and the Big Bang. It is important to note that there are inaccuracies in this intro song, so it makes for good review, discussion, and/or an assignment (confirm or refute one of the claims).
This clip illustrates the story of how Panda escaped captivity. When the zookeepers notice he's lonely, they give him a stuffed animal friend, to whom he grows attached. They plan an escape, and Panda ultimately has to leave his best friend behind.
This clip illustrates Ice Bear's origin story. While hunting one day, Ice Bear comes across a tent with some food. The human who owns the tent, Yuri, attempts to harm Ice Bear but ends up taking him in to do chores in exchange for food. One day, Ice Bear angers Yuri by accidentally causing him to break a precious photo, and Yuri kicks Ice Bear out of the tent. Ice Bear later gets stuck in a bear trap and is in peril when Yuri comes to his rescue.