### Lesson: Codebreaker Math

Author: Marc Sheehan

Subjects: Math, Social Studies, Reading

Instructional Level: Second/Third

Skills: Addition, Subtraction, Reading, Writing

Time: 45 minutes

Materials: 2 worksheets for each student (code-breaking, re-coding), pencils

Objectives: The students will correctly answer 26 addition and subtraction problems. The students will also correctly decipher a coded message. Finally, the students will correctly put a message into code.

Introduction: The lesson will begin with a short discussion on the Navajo code talkers from World War II. The Navajo code talkers took part in every assault the U.S. Marines conducted in the Pacific from 1942 to 1945. They served in all six Marine divisions, Marine Raider battalions and Marine parachute units, transmitting messages by telephone and radio in their native language--a code that the Japanese never broke. The students will conduct their own exercises in decoding and re-coding messages using math problems.

Further Background Information on Marine Codetalkers

Procedure: Each student will receive a worksheet: one half will contain a set of addition and subtraction problems that will help the students break a code (example: A = 3 + 1 = 4). The students will then complete the other half of the worksheet that will ask them to decode a message (example: 4, 1, 3 -- "the") and then put another message into code.

Sample Worksheet

Closure: After decoding the first message, the students will put a written message into code using the same parameters as before. If students wish to continue, they may take turns creating new coded messages and decoding those messages.

Assessment: The worksheets will be collected to determine whether the codes were correctly "broken," whether the problems were answered correctly, and whether the messages were correctly decoded and put into code.

Modifications: Problems can be altered, using not just one-digit numbers, but two-digits, three-digits, etc. The problems can require the use of borrowing and/or carrying. Multiplication and division problems can be substituted for addition and subtraction problems. Different students can use the same codes, but they do not have to use the same mathematical processes to determine the codes (e.g. some students can use subtraction problems that require borrowing, others can use problems that do not require borrowing).

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