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Water

Author(s): Nancy Moreno, PhD, and Barbara Tharp, MS.

What Makes Water Special?

Water molecules are attracted to each other because, in many ways, they act like tiny magnets. Each molecule in liquid water has a positive end and a negative end. The forces of attraction between these opposite charges bring the molecules together very tightly. Attraction among molecules of the same kind is called cohesion.

The forces of attraction among the molecules in most liquids are not as strong as those that occur among water molecules. The “stickiness” of water accounts for much of its behavior, including the formation of rounded droplets and its ability to creep upward inside a narrow tube (capillary action).

In this activity, students discover some of the unique qualities of water and compare and contrast water with another liquid (mineral or salad oil) that behaves differently.


Procedure
Session 1: Examining Liquid 1

  1. Demonstrate the use of a pipet (or dropper) by placing several drops of Liquid 1 (water) on an overhead projector or under a document projector.

  2. Ask students to describe the drops being projected. Explain that they will be examining drops of two different liquids at their own working areas.

  3. Have the Materials Managers collect the supplies from a central location. Each student should prepare a working surface by placing the wax paper over the graph paper.

  4. Have the students practice making equal-sized drops of Liquid 1, sharing the dropper and using the graph paper as an approximate guide to size. Students should examine the drops with their hand lenses.

  5. Ask the students to draw a drop from the side and top on their student sheets, and to describe the drop using at least three descriptive words.

  6. Next, ask the students to try to split one drop into smaller drops using a toothpick. They should draw the results on their sheets.

  7. Have the students push two drops together and discover what happens. Have them draw the new drop that forms when the two smaller drops come in contact.

  8. After forming the new larger drop, students should dip their toothpicks into a drop of food coloring and mix it into the new drop. Have students draw the drop again and color it appropriately. 

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932


Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education