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Lesson Topic_ Soil Infiltration

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					Lesson Topic: Soil infiltration experiment and analysis
Class: 7th grade                                      Timeframe: 2-3 class periods

Instructional Objectives: Students should be able to:
   1. Compare and contrast the infiltration rate of different soil textures
   2. Describe how different soil textures affect the ability of plants to use water
   3. Create a table and graph experiment results using Excel

Introduction:
    1. Think about the soil textures from last week; this lesson is about how different soil textures
       affect the plants that grow on the soils
    2. Vocab: Infiltration- When water soaks into the ground because of gravity

Activity 1
   1. Play water flow game. In three sessions: students are sand (arms out), silt (hands on hips) and
       clay (arms at side) particles. Other students are water molecules that move through the
       particles.
   2. Which particles were easier to move through?

Activity 2
   1. Demonstrate how to conduct the experiment
   2. Groups of three. Student roles: (1) measurer, (2) timer, (3) water pourer/recorder.
   3. Create a hypothesis for which of the soil textures will have the fastest infiltration rate
   4. Measure 200 mL of water. Pour water through the sieve can and begin timing the infiltration.
   5. Record measurements and times on worksheet; calculate infiltration rates.
   6. Students answer questions on handout either in class or as homework.

Activity 3
   1. Graph soil infiltration data using Excel. Suggestions:
           a. Bar graph of infiltration rate of each texture
           b. Scatter plots of % clay (or sand…) versus infiltration rate

Discussion
   1. Plants and soil:
       a. What happened? Was your hypothesis correct?
       b. How might this affect plants? Where do riparian plants get their water? (Draw)
       c. How do plants get water? (Draw a tree and show water movement)
       d. Plants use water trapped in the soil to grow. Different types of soils hold on to water
          differently: clay holds water very tightly, meaning that the water stays in the soil, but plants
          have to work harder to pull the water into their roots. Sandy soil allows water to drain
          downward by the pull of gravity, but is easier for the plants to extract.

Materials per group:
  1. Soil types (3 or more) in clear plastic                 4.   Water in cup
      cylinder (e.g. cut water bottle), labeled              5.   Can with holes in bottom (sieve)
  2. Rubbermaid tub                                          6.   Measuring beaker
  3. Stop watch                                              7.   Per student: worksheet.

Assessment: Soil infiltration worksheet and Excel tables and graphs

				
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