Materials:

• Toothpick
• Lemon juice
• Paper
• Heat source
• Vinegar or milk

1. Dip the tip of a toothpick into lemon juice
2. Then use it to write a secret message on a piece of paper
3. Use lots of lemon juice for each letter you write
4. Allow the paper to dry until you can’t see the writing anymore
5. Now move the paper back and forth over a heat source, such as a lightbulb or iron
6. As the ink gets warm, your message is revealed!

The acid in the lemon juice breaks down the cellulose of the paper into sugars. The heat supplied tens to caramelize the sugars, making them brown and revealing the secret writing. Repeat this with vinegar or milk to find out which makes the best invisible ink!

Materials:

• Sugar
• Measuring cup
• Nonstick pan
• Stove
• Large wooden spoon
• Water

1. Measure ½ cup sugar into a deep nonstick pan
2. Place the pan on the stove over low heat
3. Continuously stir the sugar as you gradually increase the heat
4. Remove the pan from the heat when the sugar is yellowish
5. Slowly add ½ cup of water to the caramel
6. Place the pan back on the stove over low heat, and stir the mixture until the caramel dissolves in the water
7. When it has cooled, taste the mixture!

Caramel is a combination of sugar and carbon. The sugar has been converted to caramel through a chemical reaction. If you heat the sugar too long, it will turn the dark brown color of carbon and lose all of its sweetness- an interesting chemical change but not very tasty!