What Scientists Cannot Yet Explain: teacher key

Hiccups, Sneezes and Yawns, grade 12 edition, written for 12th grade and up. A sneeze has a control center in the brain and a messenger molecule, one theory traces the hiccup to amphibian ancestors, and several rival ideas try to explain the yawn. Here is the evidence for each, and what is not known.

Read the book. Print this page for the key.

Questions and answers

1. What does the sneeze-evoking zone do in the sneeze reflex?
   • It makes the ears pop
   • It is the main central hub for signals from the trigeminal nerve (answer)
   • It closes the glottis
2. What did the 2025 paper say about the three photic sneeze theories?
   • The first one is proven
   • All three are false
   • No solid evidence picks between them (answer)
3. Why is the 2016 Spanish study on photic sneezing hard to rely on?
   • All 13 people studied were from one family (answer)
   • It used only mice
   • It was never published
4. Which fact about Charles Osborne's hiccup total is stated?
   • It was counted by doctors
   • It is an estimate, not a count (answer)
   • It was exactly 430 million
5. What does the Vienna study suggest about contagious yawning in a group?
   • It makes the group sleepy
   • It happens only in summer
   • It could help the whole group stay alert (answer)
6. What does debunked mean in "modern research has largely debunked this idea"?
   • Shown to be false (answer)
   • Proved true
   • Forgotten

Words

• reflex: automatic body action
• medulla: lower brainstem
• photic: about light
• glottis: throat gap
• hypothalamus: brain region
• empathy: sharing feelings