How can a bodily function be contagious? It is a question scientists and psychologists are still grappling with, but some of the leading hypotheses are presented here in the case of the contagious yawn. Most likely, it is something we have all experienced; we see or hear someone yawn (or even talk about yawning), and we just can't help but yawn ourselves. Is it a physical or psychological effect? Decide for yourself after listening to the ideas presented. Before introducing the video, it may be a fun anticipatory set to yawn in front of the class, then count how many kids yawn in response. Have learners generate a list of why they think yawns are contagious, then watch the video to see what the scientists have to say.