What Makes Water Special?
These are some ideas you can use to further your students’ inquiry into the behavior of liquids, particularly water and oil. Answers are provided.
Create a wave inside a bottle. Add equal parts of water and oil to a bottle or container that can be tightly sealed. Have students investigate what happens when they add the two liquids together. Ask them, What happens when you shake up the bottle? Next, add some food coloring. Ask, Where does the food coloring go? Why?
Oil and water do not mix. Water molecules are attracted strongly to one another, and will exclude the oil, which forms a separate layer. The oil layer will float above the water because it is less dense. When you shake the bottle, the oil is temporarily dispersed through the water, but the two liquids will eventually separate again. When you add a drop of food coloring, the water-based and less dense coloring sinks below the oil and mixes with the water underneath. The resulting bottle looks similar to a lava lamp.
Water Drop Races.
Have students use toothpicks to push water drops along the wax paper (or tilt the wax paper up and have the drops run down it) as quickly as possible. Ask them, What size of drop moves the fastest? What else affects how quickly the drop can be pushed?
Smaller drops move faster than larger drops. The surface on which the drop sits also can affect how fast it moves. Wax paper is neutral, so the drops are not attracted strongly to the surface. On the other hand, plastic wrap may slow down the water drops due to static charges, that attract and hold the polar molecules in water.
- Moreno N., and B. Tharp. (2011). The Science of Water Teacher’s Guide. Third edition. Baylor College of Medicine. ISBN: 978-1-888997-61-3.
- National Science Foundation. (2005). The Chemistry of Water.
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Funded by the following grant(s)
The Environment as a Context for Opportunities in Schools
Grant Numbers: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education