If you pay children in kindergarten to make things from modeling clay, and then stop, you may find that they are less willing to do it for nothing than they were before you ever started paying them. This is an example of?

overjustification

Explanation:

The overjustification effect is a situation that occurs when an incentive like prizes or money or prizes leads to the reduction in an individual's intrinsic motivation that is necessary in performing a task.

In this case, because the children are motivated by money, when the take doesn't involve money anymore, they may not be willing to do it.

i think it's 35 meters