question: Write a question you would see in a school textbook.
answer: Index fossils help scientists estimate the age of a rock because index fossil species only existed for a relatively short time. What happened to the species that are now used as index fossils?

question: Write a question you would see in a school textbook.
answer: While a sailor was out fishing, he got lost at sea. Which object would help him direct the boat back to shore?

question: Write a question you would see in a school textbook.
answer:
Which of these environmental changes goes on for months or years?