Question

An experiment is designed to test the relationship between the initial height of a basketball before it is dropped to the height of its rebound bounce. The height of the rebound bounce is measured using a scale positioned behind the ball.
In the above experiment, which condition would not be controlled?

Answer 1

In general, when coming up with the experiment, it's fascinating to control all factor which will have an effect on the end result of the experiment. To observe, this is often not simply gettable.
I imagine it'd be hard to manage the temperature during this experiment. although, the temperature will have an effect on the ball's bounce. 
Keep in mind that even if you do not management one thing it still is often measured then you'll be able to use that information to correct your predictions.
Explanation:

Now an uncontrolled variable is something like a force of nature, size of one thing or it's physically that cannot be controlled or modified.

An uncontrolled variable, or intermediator variable, is that the variable in an associate experiment that has the potential to negatively impact the link between the independent and dependent variables.

Answer 2

In general, when designing the experiment, it is desirable to control all thing that can affect the outcome of the experiment. In practice, this is not easily obtainable.
I imagine it would be hard to control the temperature in this experiment. Even though, temperature does affect the ball's bounce. 
Keep in mind that even if you don't control something it still can be measured and then you can use that information to correct your predictions.