“Introduction to Rocks”
Rocks are more a part of our daily lives than most people realize. One way to start students thinking about rocks and how important they are to us is by “teasing” them into realizing the different ways rocks are used every day.
ACTIVITY
Here are some examples of questions you can ask:
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1) How many of you brushed your teeth this morning? You did it by squirting rocks all over your toothbrush, right? (from fluoride)
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2) How many of you have babies in the house? When you change their diapers, do you dump rocks all over the babies to make them soft and dry? (talc rock—talcum powder)
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3) How many of you like to each McDonald’s french fries? Do you like them best covered all over with rocks? (halite)
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4) At school do you write your papers with a rock? (graphite)
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5) Do you write on the blackboard with a rock? (chalk)
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6) Do some women rub rocks all over their eyes to make themselves look beautiful? (mica)
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7) We build our houses out of rock walls which are held together by other rocks, correct? (gypsum—wallboard / hematite—nails)
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8) Is it true that electricity travels to our houses through rocks? (chalcopyrite—copper wire)
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9) Do some people burn rocks to keep themselves warm? (coal)
HOW ROCKS ARE FORMED
There are three types of rock, each formed in a different environment (weather, air, temperature). 1) HOT rocks (igneous) formed when hot, liquid rock (magma or lava) cools and hardens. 2) WET rocks (sedimentary) usually form in or near water when small particles of other rocks or sediments become cemented together. These rocks often indicate ancient seas and riverbeds, many rich in fossils of creatures that lived there millions of years ago.
The last type is 3) CHANGED rocks (metamorphic)—like a butterfly changes. These rocks form deep beneath the earth’s surface when there is enough heat and pressure to change (but not melt) the different already-existing rocks and minerals.
(figure available in print form)
