Elementary Science: Chemical Testing

One of the things I love about teaching in general, and teaching science in particular, is watching kids just sort of lose it when they make an exciting discovery.  That’s been happening quite a bit recently in my elementary science class.  (Excited squeals?  Check.  Jumping up and down?  Check.  Begging to take test strips home to show family?  Check.)  This is the first time that most (all?) of the students have used chemical tests to uncover information, and it is fun.

glucose testing
Here, kids are testing for the presence or absence of glucose using test strips designed for use by diabetics.  A few classes ago, they used dilute iodine to test for starch.

One of my main goals for this unit is that by the end of it, students should understand that we can get information about substances by running chemical tests, but each test can reveal only specific information.  This may sound rather obvious, but it is a common misconception that scientists can “test” a substance (perhaps with a microscope) and then know everything there is to know about what it is made out of.  This misconception can eventually become quite an impediment to understanding how science actually works.  Although we’re only about one-third of the way through the unit, I feel like this message is being received by students and fully integrated into their understanding of the way the world works.

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