Part 1: Conduct the Lab

1. Ask students the following questions:
   • What are some of the different variables involved in handwashing? (Washing or not washing, using soap or no soap, the time spent washing hands, the temperature of the water, scrubbing hands versus just rinsing.)
2. Have students develop a lab to discover the best method for washing their hands.
3. How could we test whether or not handwashing has been effective? (To determine the most effective handwashing techniques, you can use Glo Germ™ and an ultraviolet light or cinnamon and cooking oil to represent “bacteria.” Students can test which of the following actions gets rid of the most bacteria:
   • Cold versus warm versus hot water
   • Scrubbing versus not scrubbing hands
   • Using soap versus not using soap
   • Length of time spent scrubbing (20 seconds is the recommended amount of time for effective handwashing)
     • Note: Students can also use Petri dishes to sample hands before and after handwashing.
4. Have students form teams of 3 to 4 students. Ask each team to design a lab or activity to investigate handwashing. They can choose to show how germs are spread by poor handwashing habits, the effectiveness of different handwashing techniques in reducing bacteria, or they can investigate their own handwashing hypotheses.
5. Have students write down their research questions, hypotheses, and the procedures they plan to use. Challenge them to include the scientific principles behind their hypotheses and findings.
6. Let each team present its hypothesis and experimental design to the class. Encourage all students to discuss the merits of each suggested test. After the class discussion, give the teams time to revise their hypotheses and experimental designs if they wish to.

Part 2: Conduct the Lab and Record and Report Results

1. Have students conduct their labs.
2. Ask students to observe and record results, then create a chart or graph to show their data. Complete the lab by having the teams write their conclusions.
3. Have the teams present their results. Encourage students to include any problems they may have had and what they would do next time to avoid those problems. Remind them to explain the science behind their discoveries.
4. Let’s rejoin Dr. X to see why he’s so concerned about a problem in Sector 17.
5. Prepare students for the video clip by telling them that they will be finding the answers to these questions:
   • The Barkley family learned about the importance of washing their hands. What could have contaminated their hands before they sat down to eat dinner? (Playing with the dog, sneezing into hands, taking out the garbage, playing basketball.)
6. Why is handwashing so important both at home and in the retail setting? (Our hands are in contact with bacteria in all settings. It’s necessary to wash them just before food preparation, whether at home or in a retail setting.)
7. Can you think of other things that you touch that contribute to the spread of bacteria? (Students should contribute their own answers.)
8. Show video Module 4, Part 2 — Home (Time: 2 minutes).