Introduce the lesson by writing the following message on the board: gokod cmoprnaintg sptuvderntxs! Ask the students to try to decipher the message in their science journals. After giving them a few minutes, ask? "What does the message say?" (Good Morning Students!) Ask the students if they recognized a pattern to help them decipher the message (cross out every 3rd letter). As a class, make a list of other "ways" people communicate using a "code" and make a list on the board (texting, sign language, Braille, Morse code, semaphore, smoke signals, pictures, etc.). Facilitate a discussion about why people might use codes. Introduce the Vocabulary word Steganography and define it as the practice of hiding secret messages in other text or data.
Show the video First Telegraph Message.
Pass out the Morse Code Alphabet Sheet. Have the students follow along on the sheet as they watch the video. Show the video Morse Code Alphabet. Ask students to try to tap out the example at the bottom of the worksheet using their pencils. Can they decipher the message? (I need a map of the area immediately).
Show the video Navajo Code Talkers. Ask the students, "Did you notice differences between the secret messages sent through Morse Code and the secret messages sent by the Navajo Code Talkers?" (The Code Talkers were speaking an actual language, but Morse Code replaces the current alphabet. Also, the Navajo actually speak their secret code by a human voice while Morse code is generally delivered using a series of sounds or flashing lights). Remind the students that Morse Code continues to be recognized today by many people as a universal distress code. Explain that the practice of steganography follows a particular pattern and ask the students if they could recognize any patterns in either the Morse Code or the Navajo Code (a series of dots and dashes in Morse Code).
Pass out the Braille Alphabet Sheet (see attachment) and the Semaphore Signals Sheet (see attachment). Pass out materials for students to use for practicing secret codes (wooden sticks, small flags, bells, whistles, flashlights). Pass out the Steganography Comparison Sheet (see attachment) and place the students in groups with 4 students in each group. Using the Steganography Comparison Sheets, the students will test different secret code techniques and compare advantages and disadvantages of each technique.
After groups have had some time to explore the materials, ask the following:
- What are some of the similarities in the steganography techniques?
- What are some of the differences?
- Which one of these techniques do you think would be best for personal use? Intellectual? Military? Why or why not?
Pass out the Design Your Own Secret Code Rubric (see attachment) and say, "Now it is your turn to design your own code. Allow groups time to design their own secret code which follows a distinct pattern with a key and test their code within their group. Each "secret code" must contain at least 5 words. Example: My favorite food is chocolate. And contain a key for deciphering. Then the groups will exchange their coded message with another group to attempt to decipher.
Facilitate a discussion about digital technology and how secret messaging has changed with the use of technology (image stenography, audio stenography). Pass out How Technology Has Changed Steganography Worksheet (see attachment). Students will choose one of the following activities to complete: create a QR Code Scavenger Hunt for your class using the Classtools website or send an email in Morse Code to your Principal or Assistant Principal with the title of each group member"s favorite book in our school library using the Morse Code Translator Website.