Making invisible lemon ink
Entertaining experience To conduct the experiment you will need: half a lemon, cotton wool, match, a cup of water, a sheet of paper.
Squeeze the juice from the lemon into a cup, add the same amount of water.
Dip a match or a toothpick with wound cotton wool in a solution of lemon juice and water and write something on paper with this match.
When the "ink" is dry, heat the paper over the included table lamp. Words previously invisible will appear on paper.