Soils
Lesson 10
Why Do Plants Have Roots in Soil?
View of roots growing in a humus tube |
Students plant cucumber seeds in plastic tubes containing each of the three soil types in order to observe the roots. They will also observe the role soil plays in helping plants get water.
3. Lesson set up and Management
SYSTEMS 1.1-Properties: Understand how properties are used to identify, describe, and categorize substances, materials, and objects and how characteristics are used to categorize living things
GLE 1.1.5 Understand physical properties of Earth materials: Sort rocks based on size, shape, and other physical properties and Explain how some Earth materials are used by living things.
GLE 1.1.6 Understand characteristics of living organisms: Identify observable characteristics of living organisms and Observe and describe characteristics of living organisms.
SYSTEMS 1.2-Structures: Understand how components, structures, organizations, and interconnections describe systems
GLE 1.2.6 Know that living things are made of small parts.
GLE 1.2.7 Understand that plants and animals have life cycles.
SYSTEMS 1.3-Changes: Understand how interactions within and among systems cause changes in matter and energy
GLE 1.3.8 Know that most living things need food, water, and air.
GLE 1.3.10 Know that plants and animals need a place to live.
Roots close-up |
- Many factors, including soil, affect plant and root growth.
- Different soils absorb water at different rates.
- Roots are important for carrying water and mineral nutrients to the rest of the plant.
3. Lesson set up and Management
A 9oz. cup is a test tube holder |
Materials:
Soak 45 cucumber seeds overnight before this lesson in paper towels saturated with aged water. That will provide 3 seeds for each pair of student partners.
Have a milk jug of aged water (water that has been allowed to sit in the jug with the cap off for 24 hours to remove chlorine) on hand.
Any clumped humus or clay will need to be broken up with a tongue depressor or mallet (for the clay) to allow it to go into the narrow tubes easier.
Student Management:
It is easy for the cotton ball to become dislodged if students tamp the soil into the tubes too rigorously or pour the water too fast. One student should hold the cotton ball in place with a finger while the other pokes the hole for the seed and waters with a dropper.
Insert a cotton ball into a test tube. |
Getting soil into a test tube. |
Take time to demonstrate the proper way to plant the seed, as students often do not get it planted right next to the side of the tube and then cannot observe root growth as easily. Dampen the soil in each tube with a few drops of water (this holds soil in place a bit better), hold the tube at an angle and make a hole with the wooden stirrer right next to the downward wall of the tube. Place the seed on the tube wall and use the stirrer to slide it into the hole about a centimeter deep. Gently use the stirrer to cover the seed slightly with soil.
Image of a student's science notebook entry. |
Writing Support:
Students can draw and label the three tubes and write the steps they followed to plant each seed. Labeled diagrams are an important part of scientific writing.
Reading Support:
The reading selection "The Earthworm Nature's Plow" is available in the Soils teacher's manual to copy for each student to read and place in their science notebooks.