Yawn

Yawning is when you take a really big breath in and then slowly let it out. People often yawn when they are tired or bored, but they might also yawn when they see someone else yawn or when they are in a room with low oxygen levels. Nobody really knows why we yawn, but some scientists think it might help our brains wake up or cool down. Yawning is also contagious, which means that when one person yawns, it can make other people yawn too!