Thursday, January 28, 2010

General Science: Iodine as Indicator

This week the kids learned how to use an INDICATOR, a compound that changes color when it comes in contact with a particular substance. The kids were given around 10 different foods to test using iodine, an indicator that changes from orange to black on contact with starch. As they made their way through the food samples (testing them, not eating them), they were able to refine guesses about what starches have in common. Finally, we concluded that starches come from plants and are how plants store simple sugars.

Afterward we discussed how simple sugars are connected by chemical bonds to make complex sugars and conversely, how the chemical bonds within complex sugars are broken to produce simple sugars. Try chewing on a cracker for a few minutes (works best with unsalted ones), and you'll notice a sweet taste in your mouth that results from your saliva breaking down the starch into simple sugars.

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