Hobbies And Interests
Crystal Formation
Crystals are attractive for their interesting, geometric shapes. Discuss crystals with students and look at some naturally formed crystals, such as quartz. Then grow some of your own crystals with Epsom salts. Put some small pieces of sponge in the bottom of a plain pie pan. Mix 1/4 cup of Epsom salts with 1/2 cup of very warm water until thoroughly dissolved, then add a drop or two of food coloring. Pour the mixture into the pan and wait. Measure and observe the crystals daily. To make the experiment more complex, ask the students to guess whether temperature has an impact on crystal size, and put crystal pans in different locations around the room, including under air vents and in front of sunny windows.
Floating Rocks
Children are aware that rocks sink if put into water. However, that is not true of all rocks. Bring in some small pieces of pumice or, if possible, similar-sized pieces of other volcanic rocks, like obsidian. Put an ordinary stone into a glass of water to show how it sinks, and then repeat the experiment with pumice. Pumice is filled with pockets of air, which makes it less dense than typical rocks. To make the experiment more complex, weigh the rocks beforehand and use two rocks in the demonstration that have nearly the same weight.
Absorbant Rocks
All rocks have different properties, even if they look very similar. Chalk is a very soft mineral that can be scratched with a fingernail. Ask students if rocks can absorb water or if they think that water slides off of rocks. Then weigh a piece of raw chalk, and put it into a glass of water overnight. Weigh it again the next day. The chalk becomes heavier because it has absorbed the water.
Freezing Rocks
Rocks wear down in many conditions, including prolonged exposure to wind, rain and ice. This concept may be difficult for elementary school children to grasp because rocks seem so durable under ordinary circumstances. Ask children to hypothesize what they think would happen to a frozen rock. Put several different types of rocks into a plastic container after allowing students to examine them. Cover the rocks with water and place them in a freezer. Thaw the rocks once they have frozen completely, then freeze again. Repeat the process 3-5 times. Let the students examine the rocks at the end of the experiment, and ask for their observations. This will help them learn about the effects of ice on erosion.