Sick Potato

Pre-K through Grade 2

Grade 3 through Grade 6

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It is best to perform this activity after recess.

Grade Levels Pre-K through Grade 2

Estimated Teaching Time

• Initial activity: 30 minutes
• Observing and recording results: 10 minutes each day for one week

Interdisciplinary Connections

• Analyzing how environment and personal health are interrelated (Science, Social Skills)
• Understanding the importance of good hand hygiene (Science)

Objectives

Children will:

• Learn that germs grow on their hands.
• Learn that germs can grow on vegetables like potatoes and make them rot.
• Learn that handwashing and hand sanitizing help eliminate most germs.
• Gain experience in conducting a scientific experiment.

What Children Do

Children will conduct a scientific experiment to understand the importance of clean hands by demonstrating how bacteria grow when they are wiped on peeled potatoes by germy fingers.

Materials Required

• Program video
• Scientific experiment worksheet (blackline master 3.4 PDF)
• Potatoes, four or five
• Potato peeler and knife
• Large clean bowl filled with cold distilled water
• Plastic bag with twist tie or seal, one per child
• Pair of tongs
• Four boxes (shoe box size)
• Soap and warm water
• PURELL® Instant Hand Sanitizer

Advanced Preparation

• View the teacher demonstration of this experiment on the video. Note any differences in procedures and methods based on this lesson.
• Wash and sanitize your hands before handling the potatoes.
• Peel potatoes.
• Slice each potato into six approximately equal slices, one per child.
• Store slices in cold distilled water in a clean bowl.
• Label the boxes: Germy Hands, Soap-and-Water Washed Hands, Washed and Sanitized Hands and Sanitized Only Hands.

Suggested Sequence

1. Split class into four groups:
   • Germy Hands
   • Soap-and-Water Washed Hands — Send group to sink or bathroom.
   • Washed and Sanitized Hands — Squirt sanitizer into children’s hands after they wash with soap and water, and just before handling the potato.
   • Sanitized Only Hands — Have children use sanitizer but do not wash.
2. Instruct all but those children in the Germy Hands group not to touch themselves or anything that might be dirty or germy until after they handle the potato.
3. Give each child a plastic bag and a twist tie (if the bag doesn’t seal).
4. Using the tongs, fish a potato slice out of the water for each child. Tell the children to rub their hands all over the slice of potato and place it in the plastic bag.
5. Help them seal their bags tightly with twist ties if necessary.
6. Collect the bags and place them in the appropriately labeled boxes.
7. Have children complete the experiment activity sheet on a daily basis for a one-week period, either individually or in groups.
8. At the completion of the experiment, have the children determine which form of hand hygiene is best for handling food and other media.

Expected Results

At the culmination of this activity, your results should be quite dramatic. The potatoes which were touched by germy hands should have significantly more growth on them after one week than the others. Some fungi may appear due to conditions in the box.

Check for Understanding

Ask the following questions:

• What did we want to find out? (Question)
• What did you think we would find out? (Hypothesis)
• How did we find out? (Procedure)
• What were your daily observations? (Results)
• What actually happened? (Results)
• What did you learn? (Conclusion)

Extension

Experiment with other variations. Try soaking various items in water, placing them in bags, and comparing which seem to grow the most bacteria. You might try a piece of fruit or fruit peel, a nickel, a piece of cloth from an old shirt that has just been worn or a well-chewed piece of gum.

Words to Share

• Hand hygiene
• Hand sanitizer
• Hypothesis
• Sanitize