Secret Messages

Learning Resource Type

Lesson Plan

Subject Area

Science

Grade(s)

4

Overview

In this lesson, students will explore the practice of hiding secret messages within text or data known as steganography.  Students will compare advantages and disadvantages of different techniques of steganography.  Students will create their own secret code to communicate with each other.  Students will create a digital form of steganography with their group.

This lesson results from a collaboration between the Alabama State Department of Education and ASTA.

Science (2015) Grade(s): 4

SC15.4.7

Develop and use models to show multiple solutions in which patterns are used to transfer information (e.g., using a grid of 1s and 0s representing black and white to send information about a picture, using drums to send coded information through sound waves, using Morse code to send a message).*

UP:SC15.4.7

Vocabulary

  • transmit
  • transfer
  • decoded
  • accuracy
  • digitized
  • convert
  • coded
  • signals

Knowledge

Students know:
  • About digitized information transfer. (e.g., information can be converted from a sound wave into digital signals such as patterns of 1s and 0s and vice versa; visual or verbal messages can be encoded in patterns of flashes of light to be decoded by someone else across the room).
  • Ways that high-tech devices convert and transmit information. (e.g., cell phones convert sound waves into digital signals, so they can be transmitted long distances, and then converted back into sound waves; a picture or message can be encoded using light signals to transmit the information over a long distance).
  • Information can be transmitted over long distances without significant degradation. High tech devices, such as computers or cell phones, can receive and decode information - convert form to voice - and vice versa.

Skills

Students are able to:
  • Generate multiple design solutions that use patterns to transmit a given piece of information.
  • Apply the engineering design process to develop a model to show multiple solutions to transfer information.
  • Describe the given criteria for the design solutions.
  • Describe the given constraints of the design solutions, including the distance over which information is transmitted, safety considerations, and materials available.

Understanding

Students understand that:
  • Similarities and differences in the types of patterns used in the solutions to determine whether some ways of transmitting information are more effective than others and addressing the problem.

Scientific and Engineering Practices

Developing and Using Models

Crosscutting Concepts

Patterns

Primary Learning Objectives

Students will: 

1.) define steganography.

2.) identify patterns in various types of steganography.

3.) determine advantages and disadvantages of specific types of steganography and select the most appropriate utilization (military, personal, intellectual, etc.).

4.) design and transmit their own secret code.

5.) design a steganography technique using a type of digital technology (email Morse code or QR code scavenger hunt).

Procedures/Activities

Engage:

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).

Explore:

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?

Explain:

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. 

Elaborate:

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.


Engage:

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).

Explore:

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?

Explain:

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. 

Elaborate:

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.

Assessment Strategies

This lesson will be assessed based on the Steganography Comparison Chart, Design Your Own Secret Code Rubric, and Completion of How Technology has Changed Steganography.

Acceleration

Students may research digital imaging steganography by visiting this website: Petapixel and watch the video about digital imaging steganography.  Students can then create their own hidden message in a digital image using a steganography app. 

Intervention

Students who need extra support should be placed in groups with teammates sensitive to the needs of that student.  The teacher may need to more closely supervise groups that contain students who are struggling with the concepts of this lesson.

Total Duration

31 to 60 Minutes

Background/Preparation

For Teacher:  Steganography is the practice of hiding secret information inside text or data.  Steganography has been used for years by the government, especially during wars.  Some well-known examples are Morse Code, Navajo Code Talkers, semaphore flag signaling, and even the designs in quilts used in the underground railroad are considered a form of steganography.  Two organizations well known for using steganography are American Radio Relay League (Amateur Radio users) and the Boy Scouts of America. 

Each "code" contains a pattern such as reversing the letters, exchanging letters for numbers, exchanging letters for symbols, sounds, or gestures, excluding letters, etc.  It is the pattern in each "code" that essentially allows it to be deciphered or 'broken". 

With the use of technology, steganography has transformed; allowing people to easily hide messages in audio files, digital images, and computer files. Technology has also made it easier to detect secret codes in digital files. 

Children should be cautioned about safe internet usage prior to using the internet.

For The Student:  Students should be familiar with how to send and receive emails, how to use a QR reader, and how to navigate the internet.

Materials and Resources

Materials used to practice various types of steganography:

  • wooden sticks
  • small flags
  • bells
  • whistles
  • flashlights

Attachments:

  • Morse Code Alphabet sheet
  • Braille Alphabet Sheet
  • Semaphore Signals Sheet
  • Steganography Comparison Sheet
  • Design Your Own Secret Code Rubric
  • How Technology Has Changed Steganography

Technology Resources Needed

The teacher will need access to a computer and projector, in order to show the following videos:

First Telegraph Message

Navajo Code Talkers

Morse Code Alphabet

Digital Imaging Steganography

At least 4 mobile devices with QR code reader downloaded for student use

Approved Date

2016-08-21
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