Is Washing for Twenty Seconds Enough to Clean Your Hands Properly?

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Objective

The purpose of this experiment is to assess whether the standard 20-second handwash with soap effectively removes germs. Using Glow Germ and UV light, students will visually evaluate the effectiveness of handwashing in eliminating simulated contaminants. By comparing unwashed and washed hands, students will assess whether bacteria remain after washing and explore the implications for hygiene, food safety, and public health. The results will help determine if the standard handwashing practice is sufficient or if modifications, such as extended washing time or improved techniques, may be necessary.

Materials

• Glow Germ powder
• UV flashlight
• Cooking oil
• Liquid soap (e.g., Dawn or Palmolive)
• Water
• Paper towels

Procedure

Step 1: Apply “Germs”

• Students will form a line and approach the teacher.
• The teacher will add a few drops of cooking oil to each student’s hands and instruct them to rub their hands together thoroughly—covering palms, between fingers, and the back of their hands. The oil helps the Glow Germ powder stick to the hands more effectively.
• The teacher will then sprinkle a small amount of Glow Germ powder onto each student’s hands.
• Students will rub their hands together again to evenly distribute the Glow Germ powder.

Step 2: Initial Observation

• Once all students have applied the Glow Germ, the teacher will hold the UV flashlight over each student’s hands one at a time so they can observe how the Glow Germ is distributed.
• Students should take notes on the coverage of the simulated germs.

Step 3: Handwashing

• The teacher will turn on the water tap before students line up to start washing to prevent contamination.
• The teacher will dispense an equal amount of liquid soap into each student’s hands.
• Students will wash their hands for 20 seconds using soap and water.
• Students should use their elbows to press the lever (if applicable) when dispensing paper towels to avoid contaminating the dispenser.

Step 4: Inspection

• After drying, students will line up for UV light inspection.
• Students will record observations of their hands under UV light.
• Repeat the process of washing followed by UV flashlight inspection at 20-second intervals (20, 40, and 60 seconds) and record observations after each wash.

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Data Collection Table

Assessment Questions

1. What is the purpose of using Glow Germ in this experiment? (2 points)
2. What did you see under the UV light before washing your hands? (2 points)
3. How did your hands look under the UV light after washing for 20 seconds? (2 points)
4. Did washing for 20 seconds remove all the Glow Germ? Why do you think this happened? (4 points)
5. How did your hands change after washing for 40 and 60 seconds? (4 points)
6. Why is it important to wash hands properly in everyday life? Give two reasons. (3 points)
7. What advice would you give to someone who wants to wash their hands better? (3 points)

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