Encryption 1

Utah State Core from Utah Educator Network (June 2007):

Language Arts

• 1.1.1b - Listen and demonstrate understanding by responding appropriately (e.g., follow multiple-step directions, restate, clarify, question, summarize, elaborate formulating an opinion with supporting evidence).
• 6.1a - Use new vocabulary learned by listening, reading, and discussing a variety of genres.
• 6.2b - Relate unfamiliar words and concepts to prior knowledge to increase vocabulary (e.g., settlers: Indians, pioneers, farmers).
• 8 - Students write daily to communicate effectively for a variety of purposes and audiences.

Mathematics

• 2.1 - Recognize, describe, and use patterns and identify the attributes.
• 2.2 - Recognize, represent, and solve mathematical situations using patterns and symbols.

At the end of the lesson the student will have/be able to:

• Identify criteria for evaluating encryption schemes.
• Describe three simple encryption schemes.
• Encrypt and decrypt messages using the three encryption schemes.
• Use the words encrypt, decrypt, encryption, decryption, code, decode, plaintext, and encrypted text in instructions.

• Each student will need a 1" binder, and a pencil or pen.
• Each student will need the encryption 1 worksheet.

• code
• decode

• Think, Pair, Share
• Direct Instruction

1. Think, Pair, Share - secret codes.
   1. Step 1: Teacher poses a question.
      1. Ask, "If you want to send a message that no one but your friend could read, how might you do that?" Allow a few minutes of suggestions.
      2. Ask, "How could someone else read the message?"
      3. Ask, "What would the other person need to read the message?"
   2. Step 2: Students think individually.
      1. Pass out the Encryption 1 worksheet. This will guide the students through the thinking process.
      2. Have students fill out the "individual" part of the worksheet. Circulate among students to guide their thought processes if they get stuck. Younger students will need more guidance than older students.
   3. Each student discusses their ideas with a partner.
      1. Frame the partner work in a way that encourages a non-threatening atmosphere. Tell them to "share your best ideas and see if you can come up with more ideas."
      2. Have the students get with their partner. As they discuss their ideas, have them record new ideas on their worksheet.
      3. Circulate and reinforce the behaviors that create a non-threatening environment. Also encourage the students to build on each others' ideas.
   4. Students share their ideas with the whole class.
      1. Have the students share their ideas with the whole class. Encourage more discussion, and the recording of new or improved ideas.
      2. Use this opportunity to introduce new words: Encrypt, decrypt, encryption, decryption, plain text, encrypted text.
2. Direct Instruction - first encryption schemes.
   1. Review previously learned material. This material is the material from instructional procedure A. Further review will make sense if the students have not firmly grasped the concepts.
   2. State objectives. State that the objective of this part of the lesson is to encrypt and decrypt a message using two encryption schemes: Writing backwards, and using a template.
   3. Present new material. Introduce the method: writing backwards. Write a short message on the board then write it backwards. Show the students how to move backwards through the message writing each letter. If the students have access to the Internet, the URL http://www.lifeisastoryproblem.org\encryption\introencryption4_6.html can help increase understanding.
   4. Guided practice. Guide the students through the first exercise.
   5. Independent practice. Instruct the students to complete the second exercise. Allow the students time to read and absorb the material. If a student gets stuck, have another student assist them. This is a good opportunity for older students to assist younger students.
   6. Review periodically. The periodic review will be in other lessons on encryption.

• Blind students will need assistance in completing the worksheets, or compute access.

• An informal assessment will be performed by listening to student responses during discussions.
• A formal assessment will be performed by reading the students information pages.