Reflexes and Mysteries: teacher key

Hiccups, Sneezes and Yawns, grade 5 edition, written for 5th grade. Sneezes clear the nose, and hiccups come from a jerking muscle. Yawns are a puzzle, and scientists have tested more than one idea about them.

Read the book. Print this page for the key.

Questions and answers

1. What makes the "hic" sound in a hiccup?
   • Vocal cords snapping shut (answer)
   • Lungs filling with water
   • Stomach muscles squeezing
2. What does the NHS say about home hiccup tricks?
   • They cure every case
   • There is no evidence they work for everyone (answer)
   • They only work for children
3. About how many times a day do adults yawn on average?
   • Two or three
   • Twenty or thirty
   • Eight or nine (answer)
4. What does the brain-cooling theory say a yawn does?
   • Pulls in cool air that cools the blood going to the brain (answer)
   • Brings in more oxygen
   • Warms the lungs
5. Why is the brain-cooling idea called a theory?
   • It is proven for every person
   • It is not a settled answer (answer)
   • It was found by a child
6. What happened to the idea that yawns bring in more oxygen?
   • It was proven by every test
   • Studies did not support it (answer)
   • It was never suggested

Words

• reflex: automatic action
• diaphragm: breathing muscle
• theory: possible explanation
• oxygen: gas we breathe