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Espionage Techniques

All children are fascinated by espionage and spies (think Spy Kids and James Bond: 007). To spice up your unit on the American Revolution, try this "intriguing" activity.

Spark interest by discussing spy movies that students have seen or spy stories in the news. Talk about spies:

  • What qualifications should a spy have?
  • What is the purpose of spying?
  • What motivates a person to become a spy?

Tell students that while spies today use the latest high-tech devices (let them name some), spies during the American Revolution used methods that were just as effective in completing their missions—without all the fancy technology. Secret messages were sent in a variety of clever ways. Explain the three methods below, then assign students to write coded letters for a classmate to decipher using one of these techniques. To make it a valuable learning activity, require that the messages contain some information that students have learned about the British or American forces during the Revolutionary War.

  • Numbers code: This simple method of coding in which numbers are substituted for words was used by Benedict Arnold and John Andre (see the Image of the Month) and will be easy for students to replicate. Both parties (the encoder and the decoder) must have access to the same book, such as the social studies text. The formula involves finding the desired word in the textbook and assigning it a three– number code: its page number, line number, and word number (from the left). For example, "46.5.9" would translate to page 46, line 5, ninth word from the left.

  • Invisible Ink: Lemon juice, grapefruit juice, orange juice, white vinegar, or sugar water may be used to create invisible ink. Dip an instrument with a smooth point (like a toothpick) into the "ink" and write on a heavy piece of white writing paper. When held over a heat source, such as a light bulb or toaster, the message appears in writing that is lighter than the darkened paper.

  • Mask Letter: A "mask" is a template with a shape cut out of it, created to be placed over a clean sheet of paper. The secret letter is written on the clean sheet within the space of the template. Then the template is removed and words are added to each line to create an entirely different message on the page (this is challenging). If the letter is intercepted, the secret within is unreadable without the correct template. Only a person with the correct mask can read the document and understand its hidden meaning. The mask and coded message would have been sent separately so that if either one fell into enemy hands, the message could not be read. To see a fascinating example of a mask letter actually used in the American Revolution, go to http://www.si.umich.edu/spies/methods-mask.html.


This lesson was written by Beth Burney, elementary school teacher, Atlanta, GA.