Question

what is the dangling modifier

Answer 1

A word or phrase that modifies a word not clearly stated in the sentence. A modifier describes, clarifies, or gives more detail about the concept

Answer 2

A dangling modifier is a word or phrase that modifies a word not clearly stated in the sentence. So, the ball was dropped on the 10 yard line i think. 
Revised: Scrambling for the touchdown, Tim dropped the ball on the 10 yard line. 
Example: When nine years old, my mother enrolled me in medical school.