Tuesday, May 21, 2013

cracking marbles

Here is an easy mini lab: 
1) Bake clear glass marbles at 500 degrees on a metal cookie sheet for 20 minutes.
Exceeding 20 minutes has little effect on the outcome.
2) After 20 minutes quickly transfer to into a metal bowl of ice water.  
The glass cools rapidly and can be safely handled in a mater of seconds after being cooled by the ice bath but it is always best to be careful.  I told Boo about a science experiment I still remember from 4th grade where our teacher alternating between a hotplate and an ice bath split glass marbles demonstrating how repeated freezing and thawing can split rock.  We tried 3 rounds of baking and freezing with a set but none of our marbles broke in the process.  I think 2 more rounds might have gotten us there.  Boo took a few outside sealed in a plastic and a small hammer to experiment with. The marbles we "cracked" once broke easily with a few light taps, the ones repeatably "cracked" shattered on the first tap, and marbles which had not gone through the process didn't break at all.
Cracked Marbles

1 comment:

  1. That looks like a fun science experiment. My son would love it!

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