MnSTEP Teaching Activity Collection > MnSTEP Activities > Investigating Water Molecules: Adhesion and Cohesion

Investigating Water Molecules: Adhesion and Cohesion

Michelle Caldwell, Valley Crossing Community School, Woodbury, MN, based on an original activity from Oozing, Bubbling, Dripping and Bouncing Experiments, Janice Van Cleave
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Summary

In this activity students will observe and investigate some of the properties of water. They will do this as one of many inquiry lessons to learn about the properties of water.

Learning Goals

In this lesson students will observe the adhesive and cohesive nature of water and water's ability to wet a surface that is dependent upon the adhesive force of the wetting surface and the water molecules. They will speculate and test what other materials will also be able to draw in the water. Vocabulary: adhesive, cohesive, molecule, surface, wetting attract

Context for Use

This lesson will be one of many that are used to help children learn the properties of water. It will be probably the 4th or 5th activity they are engaged in during this process. They will have had several opportunities to make observations about water, describe its characteristics, and listen to several books about water.

Subject: Chemistry:General Chemistry:Properties of Matter,
Resource Type: Activities:Classroom Activity:Short Activity:Demonstration
Grade Level: Primary (K-2)

Description and Teaching Materials

Teaching Materials
drinking glass
eyedropper
cooking oil
water
paper
foil
wax paper
cotton ball
tissue

Description

Students will conduct this experiment with a partner.

  1. With the glass upside down, the student will rub 1 drop of oil on half the surface of the bottom of the glass.
  2. Using the eyedropper, the student will place a drop of water on each half of the bottom of the glass
  3. Each student will observe and draw what they see.
  4. After discussion about observations, students will predict and test other materials to see if water will wet those materials.

Teaching Notes and Tips

Water will "wet" a surface if it spreads out on the material, as the drop spread out on the bottom of the glass - the adhesion between glass and water is strong because the force of the glass molecules attracts the water molecules. Cohesion is the force of like molecules pulling on each other - the water molecules on the oil have small adhesion and so they pull in on each other and make the water into a sphere. What other materials will water "wet"?

Assessment

Children will draw what they saw on the bottom of their glass. They will list other materials that they tested and found to have adhesion with water.

Standards

Kindergarten/First Grade
I. History and Nature of Science
B. Scientific Inquiry - The students will observe and describe common objects using simple tools; they will compare and contrast common objects

References and Resources

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