1-2 Permeability Modeling

Summary

Permeability is the ability of water or other liquids to flow through a material. Different substances such as soil, gravel, sand, or asphalt have varying levels of permeability. In this activity, students explore permeability and compare different materials. They are introduced to the basic concepts of building design, landscape architecture, and environmental pollutant transport. This is an in-class group activity.

Engineering Connection

Environmental and civil engineers consider the permeability of the ground around major construction projects when designing drainage systems. Carefully planned systems can reduce pollution from runoff and prevent flooding. During this activity, students experiment with the material property of permeability and discuss applications for materials that are more or less permeable.

Learning Objectives

After this activity, students should be able to:

Identify different materials based on their level of permeability.
Identify and explain which materials (permeable vs. impermeable) are better for development or agriculture in various settings (urban vs. rural) and why.

Motivation

Show students a permeability demonstration. Prepare by cutting off the top and bottom ends of a soup can. Then tape or hook the can to the edge of a table with cheesecloth on the bottom, but no material in the can. On the floor under the can, place a bucket or tray to catch the water. For the demonstration, pour the water through and let students see how it falls. Discuss permeability, that is, how cheesecloth is an example of good permeability.

Investigation Questions

What materials are permeable?
What materials are impermeable?
What are some everyday examples of permeability?
Who might be concerned about permeability?

Materials List

Each Group needs:

Empty Soda bottle with bottom cut off (4 or 1, depending on if sharing tasks in group)
Stop watch
Gravel (enough to fill one soup can 3/4 of the way up)
Sand (enough to fill one can 3/4 of the way up)
Soil (enough to fill one can 3/4 of the way up)
Marbles (enough to fill one can 3/4 of the way up)
Cheesecloth
Rubberband
Medium size mixing bowl or small bucket to catch water

To share with the entire class:

Water and sink/drain

Procedure

Before the Activity:

Gather materials.
Use a scissor to remove the bottoms of all the large soda bottles.
Lay out all materials for student groups to pick up.

With the Students:

Divide the class into groups of four to five students each.
Using the laid out materials, challenge groups to design experiments that determine the relative permeability of each substance (gravel, sand, soil, and marbles). Following is an example of an experiment that students might create.

Example Experiment:

Use rubber bands to attach cheesecloth to top end of bottle
Make sure the open end of the bottle (without cheesecloth) is facing up and the cheesecloth end is over the bowl.
Fill the bottle with any of the materials: gravel, soil, sand, or marbles.
Pour water through and use a stopwatch to determine speed.
Make sure each student in the group has his or her own can for the materials he or she is assigned.

Steps for Each Bottle:

Fill a cup with water.
Hold the upside-down bottle over the empty bowl.
Slowly pour the water (through the non-cheesecloth end) into the bottle. Make sure the can is held over the bowl.
Write down observations about permeability and how fast the water traveled.
Measure the amount of water that permeated through the can and fell into the bowl.
Record observations and discuss group conclusions.