Soil and Exploration
by Ruth Ann Carlson
Zana Snell
Bill Lombardi
Trish Donovan
Grade Level: 4
Subject: Science
Duration: 45 minutes
Description: The purpose of this lesson is to make students aware of the importance of soil. They will learn about some different types of soil.
Goals:
1. Students will gain knowledge of different types of soil texture.
2. Students will gain a basic knowledge of soil and water holding capacity.
3. Students will learn about soil horizons.
Objectives:
1. Students will recognize different types of soils.
2. Students will be able to determine which soils are best for grasses.
Materials:
1. Diagram of soil horizon or actual profile.
2. Diagram of soil triangle
3. Sand
4. Silt
5. Clay
6. Loam
Preparation:
The teacher needs to find different soil types ahead of time.
Vocabulary:
1. Loam: Uniform mixture of sand, silt, and clay that may feel gritty
but does not have visible sand grains. The water holding capacity of
loam is less than clay but more than sand. It allows plants to receive
the water necessary for the growth.
2. Sand: Visible grains. A sample when wet and squeezed in the hand
will not fall apart when hand is open. Poor water holding capapcity.
Water drains quickly through sand.
3. Silt: No visible sand grains. Very smooth and floury feeling (slimy),
not sticky. Silts water holding capacity is comparable to clay.
4. Clay: Sticky feeling and may be greasy in appearance. Will make a
very tight ball that can be rolled out. Water holding capacity is great,
but it may hold the water so tight that it will not release it for plants.
5. Soil Profile: A vertical section of the different layers which make
up the soil structure from the surface to the parent material.
6. Soil Triangle: A visual representation of the three basic components
of soil and how they can be mixed together to form different textures.
Procedure:
1. Start by finding out what the students know about soil. KWL chart
is a great way to start.
2. Discuss how soil is made. It is made through wind and water erosion
from rocks.
3. Next look at a soil profile and discuss it. Make sure they know that
there is a soil profile with the different horizons (layers).
4. Introduce the soil triangle. Discuss the types of soils: Clay, Silt,
and Sand. Remember that the mixture of the three make loam which is
what we use in gardens for example.
5. After completing the discussion of soil types have the students go
to soil samples to see if they can distinguish the types of soils through
texturing.
6. When they are finished texturing ask the students how plants would
grow in the different soils and which type would be the best for plants
(Loam).
Assessment: Use the KWL chart to see what the students
learned. Also question students on soil types by having them texture
and tell whether it is clay, silt, sand or loam.