Soils
Lesson 11
Can Soil Hold Water?
Students construct a filtration system and then pour a measured amount of water onto a sample of humus to see how much water moves through the humus and how much is retained.
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 1.1.1 Understand simple properties of common natural and manufactured materials and objects: Sort common materials and objects using a simple property and Identify and describe the differences between common natural and manufactured materials and objects using properties.
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.
SYSTEMS 1.2-Structures: Understand how components, structures, organizations, and interconnections describe systems
GLE 1.2.1 Understand that things are made of parts that go together: Identify the parts of objects, organisms, and materials and Describe how the parts of objects, organisms and materials go together and Construct simple devised to do common tasks using common materials and explain how the parts depend on each other.
INQUIRY 2.1-Investigating Systems: Develop the knowledge and skills necessary to do scientific inquiry.
GLE 2.1.4 Understand that models represent real objects, events, or processes.
- Models can be constructed to test scientific concepts, such as a filtration system model for soil drainage.
- Different soils absorb water at different rates.
3. Lesson set up and Management
A funnel filtration system |
Materials:
Fold the collar of the filter around the edges of the funnel to prevent collapse of the filter.
Mark the water level in the 30 ml cups with a grease pencil or permanent marker. Have students make a matching mark on the cup that will collect the water after it moves through the humus, or pour the collected water into the original measuring cup and compare the amount of water that moved through humus to the original mark on the first cup.
Student Management:
Students often forget to place a cup under the funnel to catch the water. Be sure all have done this before water is poured into the system.
Stress the use of a dropper to pour the water onto the humus. This will prevent spills and overflows.
Students using filtration
A model and a system |
There aren't many occasions for talking about and using models in primary-grade science. The filtration system is a model of soil drainage and it is important to take time to discuss why we use a model in this instance (it makes observation and measurement of water movement through soil easier than pouring water onto the ground).
The filtration system is also a good system for discussing parts of a system, how the parts work together, and what would happen if one part was missing (particularly the collection cup!).
Writing Support:
Students can write about the variable being measured (the amount of water passing through the humus) and contrast it to the variable being measured in the next lesson (the time for water to pass through either sand or clay).
Variables are all the things that could be changed in an investigation. The variable measured is the aspect of the investigation that changes depending on how the investigation is run (depending on the manipulated variable).