Can you help me figure out the manipulated , responding, & controlled variables in the following?

Walker wanted to test how weight of a paper airplane affected the distance the airplane flew. he stood at the starting line and threw the airplane. He measured how far the paper airplane flew using meter stick. He then added 1 paper clip to each wing to make the plane heavier, threw the plan and measured. He repeated until he added 5 paper clips to each wing.

Manipulated: weight of airplane
Responding: distance flown
Controlled: paper clips & starting line

Manipulate/independent variable would be the number of paper clips, which determine the weight of the plane. Responding/dependent variable is the distance flown. Starting line and the same strength/style of the throw would be controls.