firstname.lastname@example.org Louise Huffman Kennedy Junior High 2929 Green Trails Drive Lisle, IL 60532 Activity adapted from "Sediment Tubes" by Wayne Wittenberg, teacher, Glen Ellyn, IL
Content Standard B: properties and changes in properties of matter; motions and forces; interactions of energy and matter
Content Standard D: energy in the earth system
1 Tube (18" clear plastic water-tight tube with PVC caps on both
ends, OR a clear plastic tennis ball can
4 film canisters: diatomaceous earth, sand, soil, pebbles
Hand lenses--1 for each student
Water to fill tube
Large Ziploc bag
Elaboration (Polar Applications)
2. Give time for students to examine the four materials with a hand lens
3. If the wind was to blow across these four materials, which would move in the lightest winds? Which would need a greater force?
4. Lay the Ziploc bag on the table. One partner holds it open, forming a "cave." Place 1/4 of each canister inside the lip of the bag. Use the straw to blow across the piles to see which move in the wind the easiest. Which take more force? Share ideas with the whole group. Is there agreement, or do some groups have differing ideas?
5. Ask the "Activator Question": Rivers and streams carry large amounts of sediment as they move. What happens when rushing waters of a river meet larger bodies of water and slow down? Let students discuss this in groups and share ideas with the larger group.
6. If all four materials are mixed in water, what will happen? Let students share their ideas. (Some possible suggestions: Mix and stay mixed? Mix and then separate into distinct layers? Which materials will fall out first? Then what? Some mixing, some layering? How long will it take until the water is clear? How long would it take for it to clear enough for fish to live in it? Other thoughts?)
7. Show pictures of streambeds. Would they change their prediction or leave it the same? Have small groups share their ideas with the larger group.
8. Draw a model of the group's prediction on the student worksheet.
9. Pour all materials from the canisters and from the Ziploc bag into the large tube.
10. Fill tube with water.
11. Place caps securely on the ends.
12. Shake the tube to mix all materials.
13. Set it on a flat surface and let it stand without any more disturbance.
12. Make observations over time. Compare to prediction.
Exchange (Students Draw Conclusions)
1. Diane McKnight's stream science in Antarctica--go to http://huey.colorado.edu and then follow the links to research projects and stream science
2. Discuss agricultural run-off (see "Background Information")
3. Sediment rates are measured in many different ways. Turbidity is the measure of suspended parcticles in the water. Take random river samples and measure this with a turbidity kit. (Available from Hach, Vernier, and other sources.) Turbidity could be graphed over hours and days.
4. Have students think of "stuff" that is less dense than water and would never settle. (Styrofoam, sticks, leaves, etc.) How would these additions affect the eco-system?
5. What if bones were thrown in? Which layers would be best for preserving fossils?
6. Add powdered milk to the sediment tube. It will form a solution with parcticles so small they will never settle out. The powder would look like clay but would turn to milk and stay forever cloudy. You could add this to a few tubes and watch them over several days until they realize that some parcticles never settle out. Introduce the new term "colloid."
Evaluation (Assessing Student Performance)
From the student's paragraphs, the teacher will be able to determine the depth of understanding the students have about sediment rates and sediment transport.