For his science fair experiment, Cole decided to determine how different types of surface material, affect how fast a matchbox car will go. He chose to use a tile floor, concrete patio and carpet. He
used the same car for each of the 20 trials. He measured the distances the car went after riding
down a 1-meter ramp.

What is Cole's test (independent) variable?

What is Cole's outcome (dependent) variable?

What must be kept constant (the same) for every trial?

What do you predict will happen and explain why.​