Lemon juice invisible ink

How to make it

1. 

   1

   Squeeze the lemon

   Squeeze the lemon into a bowl and add a few drops of water.

2. 

   2

   Write the message

   Dip a cotton swab and write or draw on the paper. Press firmly and dip often.

3. 

   3

   Let it dry

   Wait 10 minutes. The message disappears.

4. 

   4

   Heat the paper

   Grown-up step: iron the paper on medium with no steam, or blow a hair dryer on high close to it. Keep it moving.

5. 

   5

   Read the secret

   Watch the words turn light brown, then darker.

6. 

   6

   Talk about why

   Lemon juice has sugars and acid in it. They brown at a lower heat than paper does, a bit like toast. So the writing shows up before the paper scorches.