Simple Experiment | Making Secret Letters


There are numerous advantages to teaching science to children using everyday objects. Materials are simple to produce, inexpensive, and easy to remember for children. They can also be used to play games while learning. Making a secret letter is one of the simple experiments that can be done at home.

Secret letters can be compared to sending secret codes on a battlefield as part of a simple scientific practicum. To convey news to one other between forces separated by particular regions, like ancient freedom fighters who were guerrillas, they frequently utilize letters with special codes so that the coordination is not known to the adversary.

Secret letters are written and read in a unique way. Only the sender and recipient of the message are able to comprehend it, hence the information is not widely known. This hidden letter provides knowledge about oxidation events thanks to a simple scientific practicum.

Simple Experiment | Making Secret Letters 1
Simple Experiment | Making Secret Letters 2

Materials and Tools for Making Secret Letters:

  • Plastic or glass bowl
  • Lime/lemon juice
  • Cotton bud
  • One sheet of HVS Paper
  • Candle or hot flashlight

Steps to Make a Secret Letter:

  1. Squeeze the lime or lemon into a bowl.
  2. Dip the tip of the cotton bud in the lime/lemon juice.
  3. Make a pen from a cotton bud and write on white HVS paper. When writing on paper, use caution to avoid tearing the paper.
  4. Dry until the paper is completely dry and the writing is no longer visible.
  5. Over a candle flame (do not burn the paper) or a hot lamp, place HVS paper that has been scribbled on with lemon juice.
  6. Due to the heat generated by burning candles or lights, writing that has dried will become visible again.

Heating can cause the writing on secret letter paper to resurface. This occurs as a result of the orange juice’s oxidation process. When heated, organic components in lime/lemon flavored water oxidize and change color.

The blackening of apples after the skin has been peeled indicates oxidation activities in the fruit. Materials containing specific organic chemicals, such as vinegar, garlic juice, or whole milk, can oxidize, as demonstrated by orange juice in a simple scientific experiment.


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