Science Buddies: "Ask an Expert"

I am doing this science project for the first time. I like to ask about variables. I am investigating which wrappings best prevent sliced apples from spoiling inside the refrigerator. I have my plastic baggies, foil and wax paper as my wrappings. I've been checking my apples daily for 1 week to record spoiling (brown spots, yellowing). I am trying to understand my dependent (rate of spoilage-browning of sliced apples), independent variables (wrappings) and control (sliced apples and temperature of refrigerator). I will be using a graph to record the results. Are my variables accurate? Thanks so much.

Hello jamie2002

You've been doing your homework well! You have correctly identified all your types of variables. Congratulations!

One control variable you should pay particular attention to is temperature. Inside most refrigerators, the temperature can vary several degrees from one location to the other. You should either keep your test samples very close together, or make sure you measure the temperature inside the refrigerator at each sample location.

Another thing that can affect the rate of spoilage of produce is the environment inside the refrigerator. Some food products emit gasses when they decompose, that is spoil. These gases can affect the spoilage of other food placed nearby. One of the things a good food preservation wrapping should do is keep out those gases that can affect spoilage. That is one of the things you should be able to test with your experiment, PROVIDED each of your test sample is stored next to the same kinds of food stored in the refrigerator.

So, the best thing to do is keep all your test samples together in the refrigerator. That way, they will be exposed to the same temperature and the same spoil-inducing gases put out by other foods in the refrigerator.

Keep up the good work, and have fun!