Online Lesson Plan Fertilizers & Grass Growth
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:
- design an experiment to test the effects of common fertilizers on grass growth;
- write or present a laboratory report responding to their observations;
- and consider how fertilizers may affect the soil environment.
One of the foundations of science is being able to create an experiment to test a hypothesis. A hypothesis is a possible solution to a problem based on observations and information. (A scientist will wonder why something happens or how it happens and ask a question.) Asking the right question is important if you want an answer you can use. Try to avoid questions that are too broad, cannot be answered by very sophisticated equipment, or are unanswerable – such as, “What type of grass would grow on the moon?” Read any background material provided to support your experiment.
The question we are trying to answer is: What type of soil allows grass to grow the best?
The next step is forming the hypothesis, or possible answer to the question. A hypothesis is always a statement. After you form a hypothesis, you test to see if your hypothesis is right. As a class, brainstorm some hypotheses together to answer the question above. You can make a better hypothesis by reading the material from the web site and your textbook.
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.
Resources from outside Wessels. Find the book George Washington Carver: Plant Doctor, Soil Doctor, Multiculturalism in Mathematics, Science, and Technology, Addison-Wesley Publishing Company, Inc., and look at pages 39-40.
Materials needed for the Experiment
- Large Styrofoam cups or other appropriate container
- Grass seed
- Potting soil
- Large Shallow pan or box
- Measuring cups for soil
- 500mL beakers
- Graduated cylinders
- Distilled and tap water
- Water additives or “products”:
- Liquid fertilizer (see “General Notes” section)
- Non-diet soda
- Apple juice
- Lemon scented liquid soap
- Diluted Epsom salt solution
- Baking soda solution
- Coffee grounds
- Light source
Begin by mixing the water additives or “products” into solution. For a 1% solution, measure 5mL of product into a graduated cylinder. Pour into 495mL distilled or tap water in a 500mL beaker. For a 10% solution, measure 50mL product into the graduate. Add to beaker containing 450mL water.
Each group of students will grow the same amount of grass in the same type and amount of soil, in the same container. Each group will vary the soil fertilizer to see if it causes the grass to grow faster, greener, or have a better root system (based on their hypothesis). The soil fertilizers are the variables of this experiment!
Three days before you begin:
- 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.
Students should clearly label the cups and prepare the solutions at this time. Each “product” will be diluted in the same manner. Demonstrate using a standard amount of dry potting soil, how much liquid is too much vs. too little. Allow the class to decide how many mL of water are necessary and how often to water. Most likely you will be watering daily and skipping the weekends. Reinforce that they need to perform the experiment in the same way to eliminate any variables. Decide as a class if you will mass the soil or measure it using a standard measuring cup or beaker. Divide the grass seed equally among the groups.
- Prepare the fertilizer solutions in large jars or beakers and label. Keep all safety guidelines in mind! Students can transfer this to a graduated cylinder prior to watering. What is the control in this experiment? Discuss why these particular “fertilizers” were chosen. What makes them similar to each other? How are they different? What factors show that grass is growing well? You will also need to observe which seeds grew “first.”
- When soil is dry and ready, prepare styrofoam pots and plant grass seeds. Decide where the pots should be placed. Have students write their hypothesis. Students should have notebooks ready for data entry and may begin watering. Begin class each day after by making an observation, a notebook entry and by watering the grass seeds.
All projects should be done with supervision. Keep the following in mind:
- Wear protective eye goggles, especially when working with chemicals or a heat source.
- Do not wear contact lenses when working with chemicals.
- Do not taste any chemicals or inhale any fumes they emit.
- Keep you hands away from your face and mouth while you are working on your project. Do not eat or drink anything in the area where you are carrying out your experiment.
- Keep your work area neat and clean as possible.
- Do not use chipped or broken glassware in your experiments.
- Report any problems or injuries to the adult supervising your work.
- When in doubt, ask your teacher for advice.
Conclusion of the Lesson
Farmers have to be careful not to add too much fertilizer to their fields. They study and use math to figure out the right amount for their crops since chemicals from fertilizers can upset the balance of the soil. Grass seeds were used in this lab because they are inexpensive and grow easily. Corn is a member of the grass family and could also be used. Some of the results from the grass seed experiment could be transferred to the growth possibilities of corn.
Have students enter results onto a chart as a class visible to everyone. Include the actual grass sample for their own observations/descriptions.
Answer the following as a class and then individually: Which grass grew “best?” Which grew tallest? Which has the best color? Which grew “first?” How do the roots look? What was the best fertilizer? Why?
Use the lab report form included for Experiments Grades 6-8. Focus your scoring on the Analysis, Synthesis and Evaluation sections. Add a section on the back for sketching the grass as it grew and listing the date. You can also evaluate students as they work in their groups or as they orally present their findings.
Are fertilizers good for plants? What are some ways that household chemicals might be introduced into the soil environment? What extensions or other applications does this study have?
Use at least one commercial fertilizer such as Miracle Grow. Students will be interested to compare how the grass grows with a “real” fertilizer versus a common household product. Scotts brand starter may also be diluted into solution as a sample. It contains 20% Nitrogen, 27% phosphate, and 5% potash. Scotts turf builder 2,4D is 28% Nitrogen, 3% phosphate, and 3% potash. Each could be mixed and labeled “A” and “B.” Students will need to research ahead of time for ingredient nutrients so they may form informed hypotheses.
This lab has an extension for grades 9-12 entitled “Household Chemicals and the Environment.”
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