SEND A MESSAGE
Encoded Communications
Level: Middle/Secondary
Subject: Mathematics
Objective: Students will understand and use mathematical principles and operations to encode and decode messages.
Background: In order to prevent foreign nations and terrorists from “listening in” on our military communications, electronic transmissions are routinely sent in code. Most 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
Notional “Familygram”
Task: The teacher will create a code key using answers to mathematical problems found in their class textbooks. The mathematical problems will be substituted for the “answers” in encoding messages. The teacher will then encode the notional “Familygram” message using the code key created.
Students will create simple and mathematical codes and use them to encode messages. Students will use the code keys and messages provided by other students to decode the messages presented.
Students will then decode a notional Familygram using a mathematical code key developed by their teacher that emphasizes current or recent mathematics problems.
Activity: 1. 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.
2. 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: Teachers need not be restricted to whole numbers. Teachers can construct code keys using mathematical equations or operations that are the current or recent focus of class lessons. Students may be required to solve problems taken directly from their textbooks to derive an answer the teacher inserts into his/her own code key. Subsequently, the answer to a mathematical equation may be a number listed in the code key.. In this manner, the educator may place added emphasis on in-class focus in this example, mathematical equations using fractions and conversion of fractions to percentages).
3. Provided with a mathematical code and a coded message developed by the teacher, 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:
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.
· Interprets percent as part of 100 and as a means of comparing quantities of different size or changing sizes.
High School. The student produces evidence that demonstrates understanding of number and operation concepts; that is, the student:
· Uses addition, subtraction, multiplication, division, exponentiation, and root-extraction in forming and working with numerical and algebraic expressions.
· Has facility with the mechanics of operations as well as understanding of their typical meaning and uses in applications.
· Understands and uses number systems: natural, integer, rational, and real.
· Represents numbers in decimal or fraction form and in scientific notation…
· Compares numbers using order relations, differences, ratios, proportions, percents and proportional change.
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 - ____________________ 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 - ____________________ |
ENCODED MESSAGE
217. DEVLIN LTJG 11/30: HAPPY BDAY. KIDS SEND LUV. GIRLS MADE HONORS. MEG STARTER ON WOODBRIDGE HS BBALL. CONOR B PHYSICS SEMESTER. GREAT NEWS. COLEEN HAD BABY GIRL. ALISON. ALL HEALTHY. MONEY OK. MISS YOU. ILY. MAUREEN
The message above is a notional Familygram.
Those dreams of home and family are always at the center of the submariners’ thoughts, though there is very little the Navy can do to give them the kind of communications home that sailors aboard a carrier or frigate might have. The stealth of the modern (submarine) means that the crew …is almost never allowed to send personal messages home, and news from home is heavily limited and censored.
Word from home is limited to a series (about one a week while on patrol) of forty-word messages called “Familygrams.” Each Familygram is carefully crafted by wife, parent, or loved one to give the crewman at sea an idea of what is happening at home.
Once the Familygram has been placed into a drop box at the boat’s home base…it is reviewed by personnel at the submarine group for any security problems or for an edit or suggested change. As a general rule, no “Dear John” letters or bad news (death, illness, etc.) will be transmitted to the boat.
In addition, when the ship’s office (on the submarine) receives the Familygram, the personnel will also look over the messages and forward any that look like problems to he captain or executive officer for disposition. The Navy is quite conscious of the sacrifices of those who choose to love and live with submariners and tries to close ranks whenever there is trouble. As it is, the majority of submariners…treasure the family grams they have received over the years on cruise.
From Submarine: A Guided Tour Inside A Nuclear Warship, by Tom Clancy, Berkley Books, NY, 1993. pages 142-143.
