Refine Their Powers of Observation
Students will:
➢ Refine their powers of observation.
➢ Propose an explanation for the phenomena observed.
➢ Communicate their explanation to their peers.
➢ Support their explanation with evidence.
Materials:
➢ paper toweling (2 sheets for each group)
➢ filter paper
➢ 4 cups
➢ 1 tablespoon of “Magic Sand”
➢ 1 tablespoon of colored sand
➢ Water
➢ Spoon
➢ Pipette
Teacher Preparation:
➢ Place 2 sheets of paper toweling at each lab station.
➢ Distribute one tablespoon of “Magic Sand” and one tablespoon of colored sand on the paper towels.
➢ Place 4 cups at each lab station.
➢ Fill two of the cups approximately half full with water.
Procedure:
1. Record your observations about each of the two types of sand using all of your senses except taste! You will set up a table to summarize your observations. (Teacher Note: This is a great time to discuss qualitative and quantitative observations.)
2. AVOID MIXING THE TWO TYPES OF SAND!
3. STOP and circle the wagons! Collect observations from each of the lab groups in a class discussion of the observations made.
4. Next, sprinkle each type of sand into its own cup of water to form a “sand layer” on the surface of the water. Explore the interaction of the two types of sand with the water. (Teachers may want to suggest that students try to place drops of water on top of the “sand surface” in each of the cups.)
5. Record your explorations and your resulting observations.
6. Decant or filter the water into the empty cups. Remember to keep the water for each sand type separate.
7. Record your observations of the sand.
8. Write two or more questions you might have regarding the phenomena you have observed.
9. Construct an explanation for the behavior observed by each of the sand types.
10. Pour each sand type back into its respective water cup.
11. Add a few drops of dish soap, or baby shampoo, to each of the sand/water samples and stir.
12. Decant the water again and record your observations.
13. Record at least two questions about any change in the behavior of the sand types.
14. Propose an explanation about any possible changes observed based on the evidence collected and any prior knowledge.
15. Elect a speaker from your group to share your observations and results with the class.
Teacher Notes:
Uses of Hydrophobic Sand:
Hydrophobic sand was originally developed as a tool to mop up oil spills near the ocean shoreline. The treated sand would repel water but absorb the oil making it heavy enough to sink to the bottom where the oil could be dredged at a later time. High costs of production prevent the use of hydrophobic sand for this purpose.
Arctic utility companies utilize hydrophobic sand to bury their equipment. The sand will not absorb water and freeze. Sometimes buried equipment in the arctic needs repairs, but frozen arctic ground is difficult to excavate. Burying the equipment in the sand provides easier access to equipment should the need arise.
The sand may also be used as an aerating medium for potted plants.
Magic Sand may be obtained from Educational Innovations.
Extension:
The chemical formula for sand (silica or silicon dioxide) is SiO2. The substance coating the sand and making it hydrophobic is trimethylhydroxysilane ((CH3)3SiOH). You may want to have your students propose how these interact to produce hydrophobic sand.
TrimethylhydroxysilaneSilica as it exists in nature
“….. in every grain of sand there is the story of the earth.”
-Rachel Carson
Links to the Next Generation Framework
Scientific and Engineering Practices
1. Asking questions (for science) and defining problems (for engineering)
4. Analyzing and interpreting data
6. Constructing explanations (for science) and designing solutions (for engineering)
8. Obtaining, evaluating, and communicating information
Disciplinary Core Ideas
Physical Sciences
PS1: Matter and its interactions
Life Sciences
LS1: From molecules to organisms: Structures and processes
Engineering, Technology, and Applications of Science
ETS1: Engineering design
ETS2: Links among engineering, technology, science, and society
Crosscutting Concepts
1. Patterns
2. Cause and effect: mechanism and explanation
6. Structure and function
7. Stability and change