1. Pick two of the following body parts: mouth, nose, toes, armpit, forearm. Which do you think contains more microbes? Why? Make a prediction.
2. Put on your gloves. Place one potato slice inside a plastic bag and seal it tight. This will be your control, or the standard against which you compare your results. Use the marker to write “control” on the bag. Then place each remaining potato slice on a separate plate.
3. Use a cotton swab to gently rub one spot on your body for 45 seconds. Rub the same end of the swab on a potato slice for 30 seconds.
The potato provides microbes with nutrients to help them grow.
4. Place the slice in a bag and seal it. Use the tape to reinforce the seal. Label the bag.
5. Repeat Steps 3 and 4 with the second part of your body.
6. Set the bags aside for at least 48 hours to allow the microbes to grow. Do not open the bags for any reason. (Note: Within a few hours, parts of the potatoes will begin turning black because they’ve been exposed to the air. These black areas are not microbes.)
7. Study the potato slices inside the bags. Record your observations. Throw away the sealed bags after completing the questions below.