Suppose you have two identical sheets of paper and you crumple one of the sheets of paper into a ball. If you drop the crumpled sheet at the same time and from the same height as the un-crumpled sheet of paper, why will the crumpled sheet of paper hit the ground first?

Because it can easily resist air resistance.

Explanation:

Since air resistance is not negligible, the crumpled paper will reach the ground first because it can easily resist air resistance surrounding it compare to the un-crumpled one that will be influenced by the air thereby causing the un-crumpled paper to spend more time in the air