| An Investigation to Find Out Which of Two Rocks is the Hardest
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| 1. | You will need two different types of rocks.
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| 2. | Call one rock number 1 and the other rock number 2.
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| 3. | Rub the rocks together gently. Be careful - do not let particles of rock get
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| | into your eyes, do not rub your eyes with your fingers while you are doing
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| | this investigation.
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| 4. | If rock number 1 comes off on to rock number 2 (you can see some of rock
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| | number 1 stuck on rock number 2), then rock number 2 is harder than rock
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| | number 1.
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| | If rock number 2 comes off on to rock number 1, then rock number 1 is the
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| | hardest.
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| Now think of a way to put 4 different rocks into order of hardness.
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