Clues in the Clay: teacher key

Dinosaurs, grade 7 edition, written for 7th grade. As of November 2026, scientists link a giant asteroid to the end of the dinosaurs. Read about a thin clay layer, the Chicxulub crater and other possible causes.

Read the book. Print this page for the key.

Questions and answers

1. What does the thin clay layer at the end of the Cretaceous hold a lot of?
   • Coal
   • Iridium (answer)
   • Salt
2. As of November 2026, where did the asteroid hit?
   • In the middle of India
   • Near Colorado
   • Just off the Yucatan Peninsula (answer)
3. The Alvarezes proposed their idea in 1980. How long ago was that, if this is 2026?
   • 46 years (answer)
   • 146 years
   • 4 years
4. What did the dust and soot in the air do?
   • Made oceans warmer
   • Made plants grow faster
   • Cut down the sunlight reaching the surface (answer)
5. What does proposed mean in 'proposed that a large asteroid hit Earth'?
   • Dug up
   • Put forward an idea (answer)
   • Proved

Words

• iridium: rare metal
• extinction: dying out
• proposed: suggested
• crater: big round pit