You will need: Paper, water, baking soda, light bulb or other heat source, paintbrush/cotton swab
1. Mix equal parts water and baking soda. This will be your invisible ink!
2. Use a paintbrush, cotton swab, or similar tool to write an invisible message on a piece of paper.
3. Allow the “invisible ink” to dry.
4. Hold the paper up to a heat source (light bulb, hairdryer). The baking soda will cause the writing in the paper to turn brown.
5. Voila! The secret message has been revealed.
Tip: Don't have baking soda? Lemon juice works as well!