Now you will plan a controlled experiment. A controlled experiment is one that has a single independent variable, a single dependent variable, and all other variables held constant (controlled).

You may choose any one of the following as your independent variable: initial water amount, water temperature, can volume (if different size cans are available), or the amount of time the can is left on the hot plate. Percent crush will be the dependent variable for every experiment as that is what is being measured.

Remember whatever independent variable you choose that all other variables must be held constant. For example: if you decide to manipulate the water temperature (in the bucket), that is the only variable that can be manipulated. So in this particular experiment, the initial water amount, the can volume, and the amount of time the can is left on the hot plate must be constant in every trial conducted.

Your experiment must consist of nine trials, three trials for each data point. You will then calculate the average of the three trials at each data point. So using the above example of changing the water temperature, your group would need to conduct three trials using an ice bath, three trials using room temperature water, and three trials using hot water (while measuring the actual temperature of each for each trial).

In order to begin, your group must successfully crush a can and measure all of your variables including: initial water amount, water temperature, can volume (if different size cans are available), and the amount of time the can is left on the hot plate. These settings should be used as constants for all variables that are not your independent variable in each and every trial.