Xerox has developed 'erasable' paper in collaboration with the Palo Alto Research Centre (PARC) in California. The secret is the chemical that coats the paper. A specially designed printer 'writes' with a light beam instead of ink. The clear-coloured chemical turns a blue-purple colour when exposed to the beam. The chemical is unstable and 16 to 24 hours later, it returns to its original, clear form and the words disappear. The print can also be instantly erased by exposing the pages to heat. It can be used up to 100 times.
Children decide how they can make secret writing. They consider why erasable paper might be useful and design a poster to explain how this can help recycling.
- that changes occur when some materials are mixed
- that changes occur when some materials are heated
- that some changes are irreversible
Children will learn:
- to use scientific concepts to explain how things work
- the importance to the environment of reducing, reusing and recycling waste