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Chemical Reaction - Invisible Ink
Submitted by Sandra in Mississippi
2nd Grade Teacher
In a unit on "How Things Change" (chemical, physical changes,etc.) allow students to create their own "invisible ink". Kids will love writing a secret message in invisible ink. The message will only appear when you learn the secret method! Here's how:
1. Squeeze some lemon juice into a small cup.
2. Using a small paintbrush, dip into the juice and draw a picture or write a secret message on a piece of white typing paper. Let it dry completely. The paper still looks white!
3. Students may trade messages with friends and take them home.
4. Have an adult (Send home instructions,of course) place secret message in hot oven for a few minutes until the secret message appears. It will be written in brown and easily seen.
5. Discuss results and explain to students that when the paper is heated, water evaporates away from the lemon juice and the compound that remains mixes with oxygen and turns brown.
Students will want to repeat this over and over! If possible, this may be done right at school. Many schools have home economics ovens, ovens in teacher's lounges, or in the cafeteria. Maybe even try it using a hair dryer! That would be quick and easy!!
Webmaster note: Thanks for the great lesson, Sandra!