Reading and Vocabulary Development Unit 2 Lesson 1 Why Do We Yawn? Bears yawn. Camels yawn. Most mammals yawn. Why do we yawn? No one really knows the answer. We do know that everyone yawns in the same way. First you open your mouth slowly. Your mouth stays open for about five seconds. Then you quickly close your mouth. We also know that yawning is contagious, or catching. When you see someone yawn, you yawn, too. Many people say that they yawn because they are bored or tired. This migh
