Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Example Input: During the early paleozoic, the amount of carbon dioxide in the atmosphere was much greater compared to today.
Example Output: During the early paleozoic, the amount of carbon dioxide in the atmosphere compared to today was?

Example Input: A student should use a balance to compare the masses of two small rocks.
Example Output: Which tool should a student use to compare the masses of two small rocks?

Example Input: A(n) increase in length happens to metal railroad tracks during the heat of a summer day.
Example Output:
What happens to metal railroad tracks during the heat of a summer day?