Google Digital Literacy and Citizenship Curriculum: The lesson plans are divided into three sections; becoming a digital sleuth, managing digital footprints, and identifying online tricks and scams. By Richard Byrne.
To write an invisible message, dip a toothpick or any other sharp object in lemon, milk, white wine, vinegar, apple juice or orange juice and write on the paper. Let it dry completely. To see the message, just hold it in front of a light bulb or candle flame (not too close). The heat of the bulb will make the message appear in brown color. Read more at Buzzle: http://www.buzzle.com/articles/spy-gadgets-for-kids.html