In the Soil Is a Natural Filter Demonstration Kit for environmental science, demonstrate the ability of soil to bind and store essential nutrients. Provides a nice visual aid to tie in larger themes.
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Soil is a natural filter! Demonstrate the ability of soil to bind and store essential nutrients, and exchange them with plants, by filtering dye solutions through soil and sand. Two organic indicator dyes are used—methylene blue, which has a positive charge, and eosin Y, which is red and has a negative charge. Why is one dye retained by the soil while the other dye moves through the soil unaffected? Students observe that clay particles selectively absorb cations and learn how potassium, calcium, magnesium and other trace metal nutrients are taken up by plants from the soil. Demonstration also provides a nice visual aid to tie in larger environmental themes, such as the ability of soil to process “chemical waste” and protect against runoff and groundwater contamination. Kit includes enough chemicals and consumable supplies to perform the demonstration as written seven times, along with comprehensive Teacher Demonstration Notes and optional student worksheets.
Concepts: Soil quality and texture, cation exchange capacity.
Time Required: 20 minutes
Materials Provided: Eosin Y solution, methylene blue solution, sand, cotton balls, syringes.
Correlation to Next Generation Science Standards (NGSS)
Science & Engineering Practices
Asking questions and defining problems
Developing and using models
Disciplinary Core Ideas
MS-ESS3.A: Natural Resources
HS-ESS2.A: Earth’s Materials and Systems
Cause and effect
Systems and system models
MS-PS2-3: Ask questions about data to determine the factors that affect the strength of electric and magnetic forces
HS-PS2-5: Plan and conduct an investigation to provide evidence that an electric current can produce a magnetic field and that a changing magnetic field can produce an electric current.
MS-ETS1-2: Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.