Which ball will bounce higher, a rubber ball or a golf ball? what is the independent variable and what is the dependent variable?

The DEpendent variable is how high the ball bounces.

Some of the INdependent variables are:

--> which ball you choose to try

--> whether you THROW it down or just drop it

--> how high you throw or drop it from

--> the kind of surface it falls on .

THAT's why, when you do an experiment, you have to make sure that you change only ONE of the independent variables, and that NONE of the others changes.  

If, say, you do 2 drops ... one with a golf ball and one with a rubber ball ... and you see which one bounces higher, AND you didn't drop them from the same height onto the same surface, then you don't really know WHICH independent variable caused the result you observed.