Warm-up: What do you know about soil?
1. Using a graphic organizer, such as a KWL chart or a web diagram, begin this lesson by discussing with your class their knowledge of soil.
a) What is soil? Soil is a complex mix of materials: minerals, air, water, and organic matter.
b) What are some things we get from soil? Food, clothing, building materials, and so forth. Expand on the idea that most of our resources can be traced back to plants, animals or minerals, and therefore to soil.
c) Why might soil be called “the foundation of life”? Because nearly everything we eat, drink, use, etc. comes from soil, grows in soil, is filtered by soil, is built on soil, etc.
d) Are there different types of soil? Yes: different combinations of sand, silt, and clay.
Activity One: Sand, silt, and clay
1. To begin this activity, explain to children that there are three different types of soil: sand, silt, and clay.
2. Review the definitions of sand, silt, and clay.
a) Sand soil feels gritty, has lots of air space, and does not hold water well.
b) Silt soil feels smooth, has some air, and holds water well. When silt soil is wet, it gets slippery (think: mud).
c) Clay soil feels sticky because it is made of very small particles. It does not have much air space and does not have much room for water.
3. To better demonstrate the size of these soil particles, display and explain jars of golf balls (sand), marbles (silt), and beads (clay).
4. To better demonstrate the space between particles, pour the same amount of water into each container and observe how long it takes to fill the bottom of the jar. The water will filter to the bottom of the jar fastest in the golf balls (sand) container and slowest in the beads (clay) container.
5. Why are there different-sized particles? Soil composition and particle size depend on the materials (rocks, plants, minerals, etc.) and processes (surf, wind, moisture, etc.) in the area, as well as the age of the soil.
6. How might this particle size and filtration rate be important? Different amounts of water, or moisture levels, exist in soil depending on amount and regularity of rainfall and precipitation and rates of filtration through the soil. Different plants require different amounts of water and have adapted different root systems etc.
Activity Two: Getting to know your soil
1. Divide students into pairs or small groups. Give each student or group a copy of Reproducible #1 – Soil Observation sheet to record their results.
2. Have students rotate around a series of soil samples: sand, silt, and clay. They should observe the different samples and describe their: color, smell, and feel. They should also draw a picture of the soil particles.
3. Based on the terminology they learned in Activity 1, ask students to determine what type of soil they are examining: sand, silt, or clay.
4. After the groups have observed each sample, regroup and ask students to share their findings.
Wrap Up: Why is soil important?
- Regroup students to begin a closing discussion on why soil is important to human beings. Prompt them to think about what comes out of soil: food, clothing materials, and so forth. We build our houses and schools on soil. Soil filters our water.
- Incorporate the vocabulary and concepts from Activity One. How might different soil types affect human lifestyle in that area? The soil composition determines what kind of plants and crops grow best in each area and therefore which resources are available.
- After this brainstorming discussion, have students write a brief (1 – 5 sentences depending on students’ writing abilities) response to the question: Why is soil important?
- In order to demonstrate that soil is the “foundation of life,” consider starting a school garden or implementing native landscape on your school grounds. If it is not possible to create an outdoor garden, consider starting a container garden or window box in your classroom. Involve children in the potting and seeding process so they can see their soil at work. See http://www.earthday.net/greenschoolsrecreation for more information! You may also visit the American Horticultural Society (http://www.ahs.org/) and the National Gardening Association (http://www.garden.org/) for additional information.
- For an additional lab experience, visit http://www.earthday.net/greenschoolsrecreation for a lesson plan entitled, Let It Rain. This lesson introduces students to the concept of soil filtration how rain gardens are beneficial in cleaning up polluted waterways. Students will learn how and why rain gardens are created and then use their knowledge to build a model rain garden as part of a group.
In this lesson, students learned that soil is often referred to as the foundation of life because nearly every material we use comes from it. Students defined the different types of soil: sand, silt, and clay and visualized the air space differences within these materials. Students also articulated the importance of soil.