1.30.2010

Chemistry and Chameleons

Physical properties, by definition, are easily observed. Color, texture, odor, size, shape, taste (when appropriate) of an object can be observed simply through the five senses. To experience the concept of physical properties, students can analyze rocks or chemicals or buttons and classify them by their observable characteristics.
Chemical properties, only observable during a chemical reaction, are more complicated to explore. Waiting for something to rust or tarnish is a little painstaking. Fire and explosives are mostly frowned upon in the classroom. But since regular grape juice is an acid/base indicator, testing ph is easy, safe and basically instant. When mixed with cheap and easy-to-find white vinegar or baking soda, grape juice changes color indicating the ph of the vinegar and soda.

Enter "Color-Changing Chameleons" from Deborah Schecter's ScienceART. Using chameleon patterns from the book as a canvas for the mixture means this experiment leads conveniently into a life science lesson on the reptiles and their habitats.
First students paint the page of chameleon patterns with grape juice using q-tips as paint brushes.Let the graped chameleons dry for a few hours or overnight. Meanwhile, students can make hypotheses about how the grape juice will react when painted over with vinegar or baking soda.

Once the chameleons are dry, students should leave one alone, paint one with white vinegar, and paint the third with baking soda mixed with water. Students will immediately see the acid and base turning the chameleons greenish and bluish. Students can compare the changing chameleons to the still-purple control chameleon.
After students have collected data and developed conclusions about the experiment and whether their hypotheses were correct, these colorful chameleons can become part of an art/life science lesson.

Read Chameleon Chameleon, written by Joy Cowley and photographed by Nic Bishop, to learn about chameleons habits and habitats.
Then let students cut out their chameleons and collage them on top of a colored-in habitat.

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