Across
- 3. Scientists don't know why yawning is catching.
- 4. Scientists know why we yawn.
- 7. Yawning does not give you more _____.
- 8. to open the mouth wide and take a breath
- 9. a person who studies the natural world to find out facts about it
- 10. Some scientists thought people yawned when they were _____.
Down
- 1. Why we yawn is a _________.
- 2. One scientist thought yawning might cool our ______.
- 5. a gas in air that humans and animals need to live
- 6. to check to see how something works