SEND A MESSAGE

Encoded Communications

Level:                   Elementary/Middle/Secondary

Subject:                Mathematics

Objective:             Students will understand the relationship of mathematical principles to encode and decode messages.

Background:          In order to prevent foreign nations and terrorists from “listening in” on military communications, electronic transmissions are routinely sent in code. Many modern codes use more than a simple letter for number/letter substitution and are based in mathematics.

Materials:              2 copies of blank Russian Submarine Museum Code Keys
Coded message and associated mathematical code key

Task:                    Create a simple code. Use the code to encode and decode messages.

Activity:               Create a simple code substituting letters or numbers on a code sheet. Write a message using that code of at least 5 sentences.

                            Provide both the message and code key to another student who will

                            attempt to decode your message.

                            Create a mathematical code whereby a mathematical equation is substituted for the number derived (i.e., “5x2” rather than “10”). Students must create the mathematical code and subsequent message. The student then provides both the message of at least 5 sentences and the code key to another student for decoding.
(Note: Though students are allowed to use addition, subtraction multiplication, and division equations in the code, teachers may restrict the code to “multiplication only” if the focus of their in class instruction focuses on multiplication).

                            Provided with a mathematical code and a coded message, decode the message to find an example of a typical message periodically sent by families to their submarine aboard ship to update him on their situation at home.

Circumstances of performance: This student work is to be produced under the following work conditions:

__ alone                                  __ in a group

__ in class                               __ as homework

__ with teacher feedback         __ timed

__ with peer feedback             __ opportunity for revision

Standards addressed:

Elementary School. The student produces evidence that demonstrates understanding of arithmetic and number concepts; that is, the student:

·      Adds, i.e., joins things together, increases;

·      Subtracts, i.e., takes away, compares, finds the differences;

·      Multiplies, i.e., uses repeated addition, counts by multiples, combines things that come in groups, makes arrays, uses area models, computes simple scales, uses simple rates;

·      Divides, i.e., puts things into groups, shares equally, calculates simple rates;

·      Analyzes problem situations and contexts in order to figure out when to add, subtract, multiply, or divide;

·      Solves arithmetic problems by relating addition, subtraction, multiplication, and division to one another;

·      Computes answers mentally

Middle School. The student produces evidence that demonstrates understanding of number and operation concepts; that is, the student:

·      Consistently and accurately adds, subtracts, multiplies, and divides rational numbers using appropriate methods.

Girl Scout Advancement Requirements

Junior Girl Scouts Creative Solutions Badge          

9. Coded Language. With a friend or two, invent your own coded language. Create an alphabet using signs, symbols, pictures, or even letters from the English alphabet. You could add some foreign words to represent other words or phrases. Write a message using your secret code. Be sure to make a dictionary that explains your code alphabet.

Junior Girl Scouts Math Whiz Badge

8. Make Your Own Code. Assign the letter “A” a number value. If A=7, B would equal 8, E would equal 11 and so on. Write out a secret message for a friend, using equations to substitute for each letter. For example: If A=7, E = 11, L=18 and P=22, you could spell out the word apple by writing: 3+4, 10+12, 2x11, 23-5, 22/2. Send your friend the message and see if she can unravel your meaning. Don’t forget to share the key to the code with her!

CODE KEY

A - ____________________  U - ____________________  

B - ____________________  V - ____________________  

C - ____________________  W - ____________________  

D - ____________________  X - ____________________  

E - ____________________  Y - ____________________  

F - ____________________  Z - ____________________  

G - ____________________  

H - ____________________  1 - ____________________  

I - ____________________  2 - ____________________  

J - ____________________  3 - ____________________  

K - ____________________  4 - ____________________  

L - ____________________  5 - ____________________  

M - ____________________  6 - ____________________  

N - ____________________  7 - ____________________  

O - ____________________  8 - ____________________  

P - ____________________  9 - ____________________  

Q - ____________________

R - ____________________

S - ____________________

T - ____________________