Starch Test in Foods
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Susan Wimberly Frazier Elementary School
4027 W. Grenshaw St.
Chicago IL 60624
This lesson was designed for use in fourth grade and satisfies Illinois State
Goals 1, 3, and 4.
The student will be able to...
- confirm a prediction by doing an appropriate experiment;
- identify various foods which are starches.
newspaper small samples of food:
6 glass jars butter
tap water rice
20 plastic plates cheese
20 eyedroppers meat
20 starch charts potato (raw)
1-1 oz. bottle iodine tincture apple
(NOTE: Iodine tincture is salt
poisonous and eats through flour
1. Ask students how they enjoyed lunch (or breakfast) and what they ate for
2. On the chalkboard, make a list of some of the foods students ate.
3. Write the word "starch" on the board and ask students if they know what
4. Explain that starch is a common form of complex carbohydrate that we
need to be healthy.
5. Explain that starch is stored in plants.
6. If not already on the board, write the foods from the "small sample of
food" list above.
7. Ask students to predict, or guess, what foods on the board are starches,
and draw a star next to those foods.
8. Explain that you will test one of those foods to find out.
9. Cover work space with newspaper (iodine discolors surfaces).
10. Stir equal amounts of iodine and water into one jar.
11. Pour equal amounts of the solution into the other five jars and set aside
12. Place a piece of potato on the newspaper.
13. With an eyedropper, apply a few drops of the iodine solution to the potato.
When exposed to starch, iodine turns dark brown or blue-black.
14. Ask students what the color change means.
15. Explain that the potato is a starch.
1. Each student will receive a starch chart, eyedropper, and plastic plate
with a piece of each of the food samples listed above.
2. Each table of 4 students will receive a jar of the iodine solution to
3. Explain that the students will first record their predictions in the first
column of the starch chart, and then they will apply a few drops on each
food sample. Any change will occur within a few seconds.
4. Explain that after five minutes, students will record their findings in the
second column of the starch chart.
5. Student predictions (column 1) may vary. In column 2, the following
should be listed as starches: rice; potato; flour.
6. What do these samples have in common? They all come from plants.