Problem: Write a question you would see in a school textbook.

Answer: The continental crust floats on top of the mantle because the crust is

Problem: Write a question you would see in a school textbook.

Answer: In 1987, a supernova was detected in the Large Magellanic Cloud galaxy, which is approximately 169,000 light years from Earth. Which event produces a supernova?

Problem: Write a question you would see in a school textbook.

Answer:
One cause of heat in a car engine is caused by friction between parts. Which of these reduces the amount of heat produced by friction?