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Product No. HiMAP Pull-Out Supplementary Print Price: FREE with membership

Secret Codes

Marsha Davis, Pat Taylor

Mathematics Topic:
Algebra, Linear Algebra
Application Areas:
Experience with describing, evaluating, and graphing linear equations; matrix operations

| ©2004 Consortium 87 | 15 pages |

The activities in this Pull-Out explore several methods of coding messages.

Activity 1 opens with an easy code to crack—the U.S. Postal Service zip code. Then students are challenged to decode five secret messages.

In Activity 2 students learn about shift and stretch ciphers. Students describe these coding processes with arrow diagrams, tables, graphs and linear equations.

Activity 3 focuses on decoding. Students look for patterns in the coded messages that help them discover the coding process, and then must reverse the process to decode the messages.

Activity 4 introduces matrices to speed the coding and decoding process. In addition, students learn how to code using keyword matrices. This activity ends with an optional final project in which students must crack coded messages in order to find clues to the location of other messages. Cracking the final message leads them to a prize.

To download the Coding Utility program click on the correct format below.