Online Lesson Plan Household Chemicals & the Environment
Lesson Plan by who has taught science at both the middle school and high school levels for Lincoln Public Schools. She has written assessment and curriculum for LPS and has attained a Level II assessment certification. She has also served as a student teacher supervisor for the University of Nebraska-Lincoln.
|Suggested Grade Level:
Logical-mathematical & Naturalist
|What are these educational concepts?|
In this lab, students will:
- see how human activities affect other species;
- test the effects of household chemicals (waste) on the growth of plants (crops);
- and observe growth of seedlings, create data tables and analyze conclusions based on these observations.
Farming is essential to the survival of the human species. The yield of food per acre has grown in the last century. Modern machinery and chemical fertilizers have increased food output. Can fertilizers do damage to the soil? Do chemicals alter the surrounding environment? Could we grow crops without them and continue the yield? How do chemicals affect seed growth? In this lab, you will begin to answer these questions.
Links from within the Wessels Living History Farm site. [Note that clicking on these links will open a new browser window. Just close it and you’ll be back to this page.] Direct the students to these pages.
- The Chemical Age Dawns
- Herbicides – 2,4-D & Its Cousins
- Pesticide Regulations – FIFRA
- Postwar Fertilizer Explodes
Resources from outside Wessels. Find the book How the Environment Works, Ziff-Davis Press, 1994.
Materials needed for the Experiment
- 100mL disposable petri dishes
- potting soil
- plant food mix (optional)
- seeds: wheat, radish, lettuce
- sandwich sized plastic bags
- rubber bands or tie twisties
- marking pens
- clean silica sand
- distilled water
- tablespoon measure
- 100mL graduated cylinder
- three or four common household products-bleach, rubbing alcohol, etc.
- 500 mL beakers
- metric rulers
Line a box or large pan with newspaper and pour the soil to be used onto the paper. Have students work the soil to remove clumps and ensure an even texture. Leave the soil out over the paper to dry completely. This usually takes about three days.
Part 1: Preparing the ‘Contaminant’
This lab involves two differing dilutions of contaminant products. You may choose to use three or more and can adjust as you see fit.
For a 1% solution of contaminant: measure 5mL household product in a 100mL graduated cylinder. Add to 495mL distilled water in a 500mL beaker. Rinse the cylinder.
For a 10% solution of contaminant: measure 50mL product into graduated cylinder. Pour into 450mL distilled water in a 500mL beaker. Rinse the cylinder.
Label the beakers and set aside.
Part 2: Preparing the Seed Dishes
- Each student group will test two different percentage solutions on two kinds of seeds. You will need six petri dishes (bottoms only) per group. Two of the dishes are the control. You may wish to have groups test only one sample per seed and use class data to compare OR you may wish to have each group test three or more samples.
- Fill the bottom of a petri dish with the air-dried soil. Determine the mass of the soil and repeat for each dish in the group.
- Place 10 seeds in each dish. Be sure to keep the groups labeled so you know which dish contains which type of seed.
- Sprinkle a tablespoon of sand over each dish.
Part 3: The Contaminant!
- Measure 15mL of a contaminant solution and add it to a seed dish. Place the dish inside a plastic bag and close with a twist tie or rubber band.
- Label the bags by seed type, household product, and percentage of solution: for example, “10% ammonia-radish.”
- Repeat the steps above until your group has prepared each seed type with each percent solution.
- Measure 15mL distilled water into the dishes of each seed type. Label this as the control by seed type, for example, “control-radish.”
- Place the dishes at an equal distance from an indirect source of sunlight. They should be observed for about two weeks. Keep track of how much time they are affected by artificial classroom light.
- Record the amounts in light and in darkness in your notebook or on your conclusion page. Room temperature should be constant.
Part 4: The Data Table
- Prepare a data table for each household product tested. Some samples are given below.
- After 5 days, count the number of seedlings for each dish. Record the findings on the data table.
- After 14 days, measure and average the height of the three tallest seedlings in each dish (mm). Record findings.
- A table can also be created to show results by household product.
Number of Seeds Emerged – Day 5 Household Product _________________________________ Solution Strength Seed: ________ Seed: ________ 1% 10% Control Average Height of 3 Tallest Seedlings – Day 14 Household Product _________________________________ Solution Strength Seed: ________ Seed: ________ 1% 10% Control
Please abide by your classroom safety procedures. Household chemicals can cause burns. Wear goggles. Wash hands carefully after working. Avoid inhaling strong concentrations. NEVER mix ammonia and chlorine bleach. The fumes of the combination are poisonous. It may be best to avoid these in the sample depending on class make up. Dispose of leftover solutions by washing down the drain one at a time using PLENTY of water.
Conclusion of the Lesson
The Midwest has some of the most fertile soil in the world. Fertile soil is valuable because there is a limited supply. Less than 1/8th of the land on Earth has soils well suited for farming. Plowing, heavy rains, wind and chemicals make soil vulnerable to erosion. Farmers recognize this problem and know that good environmental practices mean higher yield and higher profits. It is possible to feed the world and care for the environment at the same time.
- Find the percentage of emergence by seed, by solution, and by product. The control should also be calculated. Compare tables by group. Calculate class average and post.
- Which contaminant had the most impact on percentage of emergence? Seedling height?
- Which product was the most toxic overall?
- Which seed was the most sensitive to contaminates?
- What happens to emergence and seedling height as percentage of contaminant increases?
- What are some ways household chemicals might be introduced into a soil environment?
- What is the value of soil to human beings and other living things?
Possible Interaction suggestions:
This lab is a continuation or expression of the 6-8 lab entitled, “Fertilizers and Grass Growth.” This laboratory involves more complicated data tables and more hazardous chemicals making it appropriate for grades 9-12. Analysis of soil chemicals, DDT, and other topics can be discussed in a debate form based on the resource material.
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