Lesson Plans in Pollution Prevention
Alternatives and Science Labs
Grade 7 (ages 11 - 13)
Science and Technology, Social Studies
After completing the exercises in this lesson, student will
- Know the meaning of toxic, and understand how toxic products can have a negative effect on natural life
- Be familiar with cleaning properties of natural, non-toxic products found in the home
- Use investigative techniques to find results and draw conclusions based on a comparison experiment
- Water, vinegar, baking soda, essential oil (optional) for every lab group
- Plastic containers that will pour well
- Access to a lab or classroom with many surfaces
- Soiling materials (mud, juice, etc,)
- Cotton cleaning rag or cloth
- Student notebooks
- Pencils or pens
- 20 minutes for discussion
- 30 minutes for lab activity
- Discuss with students the meaning of the word "toxic," with specific reference to products typically found in homes, schools, or other familiar settings. Illustrate the warning labels (skull and crossbones, etc.) to help clarify the effects of toxic substances.
- Help students to understand that once toxics are introduced into the environment, they can have negative effects on plants, animals, and other organisms. Using toxic products around the home, even carefully, can result in water, air, and soil contamination. Some examples might be rinsing cleaners down the drain or leaving containers of paint or detergent open for extended periods of time.
- Introduce several natural substances (that students may already be familiar with) as alternatives to commercial cleaners and discuss their properties. For example, vinegar and lemon juice are natural acids and can therefore kill bacteria.
- Allow students to brainstorm, in pairs or as a large group, about which natural products could be used to clean different rooms or items in their homes. Have them state why they think the products they have identified would be successful cleaners.
* Prior to commencing this lab activity, teachers should be aware of all potential safety issues with each ingredient and/or combination of ingredients and take the proper precautions to educate students about appropriate lab procedures and behaviour. If students are conducting further experiments outside of the class, they should be made fully aware of any potential safety hazards and should be encouraged to work under the supervision of an adult.
- Have students work in supervised groups of two or three to concoct their own all-purpose cleaner. Each group should have about 250-500 ml (1-2 cups) of cleaning product. Encourage students to come up with names and advertising slogans or jingles for their products.
- Spread the groups of students out around the class, so that every group has a large hard surface (desk, blackboard, etc.) to experiment on. Provide each group with a comparable amount of commercial cleaning product, as well as a cotton cleaning cloth or rag.
- Allow students to soil their cleaning area. Suggestions for soiling include rubbing dirt/mud on the surface, pouring some juice or soapy water and letting it dry, or rubbing a bar of soap on the surface to simulate soap scum. Once students are satisfied with that their surfaces are dirty enough, have them divide the area in two and mark it clearly with tape or string.
- Have students clean one side of the surface with the commercial cleaner and the other with their homemade cleaner. Allow them sufficient time to use their elbow grease for best results!
- Once students are satisfied that their surfaces are as clean as they will ever be, have them write the results of the cleaning in a table. They should try to judge the cleaners' success by using three of the five senses; how does the surface look, smell, and feel? Students can rate the effectiveness of their cleaners on a scale of 1-5, or the teacher can create a small rubric ahead of time for students to use.
- When all the groups have finished their evaluations, ask students to share the results with the rest of the class, either in the form of a quick discussion or in a large table where all the data and results are recorded.
This activity can be used as a formal scientific lab, and students could write up a report with hypothesis, materials and methods, observations, discussion, and conclusion sections. Students should be sure to include complete descriptions of their results and try to draw some conclusions as to why they achieved the results they did.
Students can carry out further experiments, either using their cleaner on other types of surfaces (chrome, plastic, linoleum, porcelain, etc.) or trying it on different types of dirt (grease, oil, food stains, etc.). Students could also venture into experiments involving other types of cleaning products, such as glass, carpet, or oven cleaners, as a research project or science fair activity. See the Resources section for ideas and suggestions.
Suggest to students that they could conduct a similar type of comparison and compare the results of their cleaners with those of commercially available "green" or eco-friendly cleaners, found in some natural, environmental, and health food stores. Have them compare the results from the first activity to this one. Which type of cleaner does the best job? If all the results are similar, which types of products would be the best to use on a regular basis?
Have students develop a line of cleaning products that are environmentally friendly. The products should include cleaners for all rooms and surfaces in the home. The line could be extended to include products for schools, office buildings, etc. The line should have an appropriate name and come with a brochure that explains what each product is designed to clean and which natural ingredients are included.
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