What you'll need
- Bicarbonate of soda
- A mug of cold water
- A few red grapes
- Paint brush
- Paper
What to do
- Put one tablespoon of bicarbonate of soda into a mug of cold water and stir
- Dip your paintbrush into the solution and paint your message on the paper
- Let the paper dry
- When you're ready to reveal your message, rub a red grape over the paper and watch what happens
- Can you work out what's going on?
- Of the red grape and the bicarbonate of soda which do you think is acidic and which is alkaline?
Disclaimer: Please follow the instructions carefully. This is for your own safety and the safety of others. Do not improvise or change the quantities or actions or othe order in which each step in the experiment is listed.