Wait, some infinities are bigger than others?

Despite struggling with math in school, I have since found a love for numbers--in large part a result of watching great videos on YouTube (shameless plug?).  Anyway, here are a few of my favorite videos on the concept of infinity. Feel free to use these as tools to help blow your students' minds. 

The universe has no edge! I bought the poster as a reminder. 

Vihart explains how to draw infinite elephants.

MinutePhysics teaches us how to count to infinity.