Secret Message

Stephen W. Ha James Ward School

2701 S. Shields Avenue

Chicago IL 60616

(773) 534-9050


Using the characteristic of a chemical reaction to write a secret letter

Materials Needed:

Soup bowl, cup (250ml), Tincture of iodine, eyedropper, lemon, lime, orange, grapefruit, notebook paper, art brush, work-table


(1) Pour half a cup of water into soup bowl.

(2) Add 10 drops of tincture of iodine to the water and stir.

(3) Squeeze the juice of a lemon into the cup.

(4) Cut a section from the notebook paper so that it will fit inside the bowl.

(5) Dip the art brush into the juice and write a message on the piece of paper.

(6) Allow the juice to dry on the paper.

(7) Submerse the paper into the iodine solution in the bowl.

(8) Record all information on the work-chart.

(9) Repeat the step three through step 8 with a different kind of fruit until all the fruits have been tried.

(10) Compare the results.

Performance Assessment:

Students can use this method to test other fruits to see if vitamin C exists in all fruits or not.


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