Anyone remember lemon juice invisible ink? What started it was Jessica got an invisible ink pen in a cereal packet and started writing secret messages on everything. Then I remembered the old lemon juice trick which we used to do when I was a kid. I looked up some websites on lemon juice invisible ink and secret codes.
We tried writing with lemon juice, apple juice and vinegar. The lemon juice turned out to be the best because it browned quicly when held near a candle. My apple juice message caught on fire because I held it too close to the candle for too long waiting for it to brown. 🙂
We also looked at different types of codes – written and spoken codes, alphabetical and symbols. It was a lot of fun and good learning too. As well as talking about secret messages we went on to computer encryption.