Teacher Notes on Soil Fractions
Objective: Exercise shaking muscles; use math to determine characteristics of soil and cleaning up area.
Materials:
Soil to be tested
At least 4 Stack Soil Sieves
Triple beam balances
Same number of paper cups as there are stacks to the sieves.
Calculators
Broom and dust pan.
Doing soil fractions is fun. It is probably the most effective tool I know of for teaching percentages and fractions. It all makes sense after you're done. It is not really biology, but it that wonderful area where biology and Earth science meet. They are doing that nowadays.
There are other ways to do Particle Size analysis. A college text for the class is
Gee, G.W.(1986) "Particle-size Analysis" Methods of soil analysis Agronomy no 9: 383
Plus LaMott makes a small kit for Soil Particle Size Analysis for $36. It is designed for the high school class.
See A-4 for assessment.
Statement of Investigative Question: What is the percentage of different sized particles in a soil?
Collecting data:
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Soil Name (potting soil etc...) |
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Mass of Rock (in grams) |
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Mass o Gravel (in grams) |
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Mass of Sand (in grams) |
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Mass of Silt (in grams) |
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Mass of Clay (in grams) |
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Total mass of cups: (in grams) |
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Calculating Percentage: Divide each soil fraction by the total mass of the soil sample. Next multiply by 100 to move the decimal point for the PERCENTAGE.
Mass of rock _________÷ Mass of soil________ = _______ X 100 = _________
Mass of gravel________ ÷ Mass of soil________ = _______ X 100 = _________
Mass of sand_________ ÷ Mass of soil________ = _______ X 100 = _________
Mass of silt __________÷ Mass of soil_________ = _______X 100 = _________
Mass of clay__________ ÷ Mass of soil________ = _______X 100 = _________
Conclusion
The soil fraction with the highest percentage was _______________________________with _____ %
Second was ____________________________with_____ %
Third was______________________________ with_____ %
Fourth was_____________________________ with_____ %
Fifth was_______________________________ with_____ %
SAVE ALL OF YOUR FRACTIONS FOR THE NEXT LAB EXPERIMENT