Friday, October 1, 2010

Experimenting With Rocks

This week in science we’ve been studying different types of rocks.  I found this nifty experiment to show how stalactites are formed, so I thought I’d share it with my readers.

What you need:

Epsom salts
2 small jars, such as baby food jars
cotton string
2 metal washers
spoon
ruler
paper
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Fill each jar with Epsom salts.  Add water to the height of the Epsom salts and stir.  Cut a piece of string 24 inches long.  Tie a washer to each end of the string.  Place on washer in each of the jars.  Position the jars so that the string hags between them with the lowest part of the loop about 1 inch above the paper.   Allow the jars to stand undisturbed and out of any draft for one week.  (Unfortunately, the inquisitive 5 year old couldn’t keep her hands out of this one….so it failed…she kept squishing out progress.)

This is what is SUPPOSED to happen!  Water containing the Epsom salts moves through the string.  As the water evaporates, crystals of Epsom salts are deposited.  The Epsom salts formations are models of how crystal deposits form in caves.

Another fun (and much faster) experiment helps children (and Mom too) understand how pumice can float on water even though it is rock.

What you need:

1 egg white
1 bowl
1 metal wisk

035Separate your egg and place the white into the bowl.   Use your wisk to beat the egg until it turns into meringue and forms stiff peaks.   Explain that just as the egg white is still exactly the same, the fact that air was forced into it has changed the texture and volume, but not the weight.   The same is true of pumice, it is simply air infused rock that is puffy but quite light.

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We also used some of our seashells from our vacation for an experiment. 

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Sea shells are made up of limestone, so we submerged a few into acid (ok vinegar, but it IS an acid) and watched the bubble frenzy commence.  After only 2 minutes our vinegar went from clear to THIS….

006Pretty gross eh?  After 24 hours some of the smaller shells had disappeared and some of the larger ones were noticeably altered.

Then to wrap it all up we made a batch of salt dough and worked on creating fossils.

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Here is Olivia’s final arrangements.  We haven’t removed the shells and leaves yet….this stuff takes a long time to dry when it’s not smooshed out very flat!

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