Preschool Science
Magic Invisible Ink

This is a cool preschool science project that you can use as magic show or use it for some spy game!

what you need:
white paper, cotton bud, lemon juice, salt

Procedure:
1. Dab a cotton bud or brush into a bowl of lemon juice
2. Start writing on the white paper with the cotton bud.
3. Simply heat the paper under the sunlight/candle after it dries.
4. You can also put salt on the drying ink, then give it a minute and then wipe the salt off.
5. You can then use a wax crayon to color over the message.

The scientific explanations:
Lemon juice is mildly acidic and acid weakens paper.
The acid remains in the paper after the juice dried.
When the paper is held near heat ,the acidic parts of the paper burn or turn brown before the rest of the paper does.

awesome stuff!