Objective: To learn about the physical properties of porous rock types.
Standards: Properties of Earth Materials (physical and chemical properties of rocks and soils).
Materials: Various porous rocks, a shallow baking pan or plugged sink, and water.
(1) Place the porous rocks in the baking pan or plugged sink.
(2) Pour in enough water to cover the rocks generously.
(3) Closely watch and observe the rocks.
Science Behind It: Streams of bubbles will flow out of the rocks. The more porous the rocks are in this demo, the more bubbles will be seen. Depending on the weight of the rocks and the force of the air leaving them, the rocks may display slight movement or oscillation in the water. These observations occur in this demo because oxygen is present in the porous rocks and flows out from the spaces between the minerals that make up the rocks. Examples of porous rocks include many igneous rocks such as pumice, scoria, and basalt.