Al wonders if adding salt to water will affect how long it takes the water to freeze. Al thinks that salt water will freeze more quickly than fresh water. He decides to check his hypothesis by conducting an experiment. Al takes two identical ice trays and fills one with distilled water and the other with distilled water that has two tablespoons of salt added. He makes sure he puts exactly the same amount of water in each ice tray. Al takes the trays and puts them side by side in the freezer, so they are at the same temperature. Al checks the ice trays every 10 minutes to see if the water in each tray has begun to freeze. Al finds that after 20 minutes the water in the ice tray without the salt has started to form ice, while the ice tray with the salt water is still completely liquid. Identify the Independent Variable, Dependent Variable and Constants (3)