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Unit 19: Biology Part 2 Page 92 of 137

Activities and Experiments

Lesson 2: Digestive System

Experiment: Magic Spit

Materials:

 Protective eyewear
 Cornstarch
 Plate
 Iodine (can be purchased at drug stores)

 Water
 Two similar sized glasses. Label them “A” and “B”.
 Measuring spoon
 Teaspoon
 Two coffee stirrers
 Notebook

What to do:

1. Put a teaspoon of cornstarch on a plate.
2. Put a couple drops of iodine on the cornstarch. Note the color.
3. Generate at least 2 millimeters of spit in glass A. (Tip: think of lemons
helps generate spit).
4. Pour 2 millimeters of water in glass B.
5. Put 1/10 teaspoon in both glasses.
6. Mix glass A with the first coffee stirrer.
7. Mix glass B with the second coffee stirrer.

8. Add two drops of iodine to each.
9. Mix and place in a warm place (i.e. direct sunlight) for twenty minutes.
10. Observe changes.

What happened? When the iodine touched the cornstarch on the plate it
turned blue-black. This is because it is a starch indicator (it always turns this
color in the presence of starch).

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