• copy of the Operation Decode activity sheets
  Part I -- HTML Version
  Part II -- HTML Version
• scissors
• paper brad

1. On the board, copy the cipher and alphabet from the Operation Decode Part I activity sheet so that the class can decode together.

2. Distribute materials and follow the instructions on the activity sheet. Before deciphering, discuss possible strategies to break this cipher. Tell students the message is from Winston Churchill to the members of Station X. If students experience difficulty, use the key in Activity Answer to provide the letters for the word "SOMETHING."
3. Students may work individually or in teams. Encourage them to share discoveries with the class, and as they decipher, print letters over each word in both the cryptogram and alphabet.
4. List all successful strategies students use to help decipher.

1. Follow the directions on the Operation Decode Part II activity sheet. (Point out that the cipher is what they will write on the outside rim.)
2. When students determine their own setup configurations, tell them the first number can be any number from 1 to 26, but the second should be no greater than 5 (as moving the disk becomes a problem).

1. Miss Elisia Valdrez: RECESS, TEACHER, CHALK, BOOK, MISSV, RETURN, SCHOOL, GRADE1, ABCDEFG

2. Michael Thomas: COACH, HIKE, SCRIMAGE, PIGSKIN, HUDDLE, FUMBLE, PUNT, TACKLE, SUPRBOWL

3. Ling: TIGGER, TIGSAM, ALGEBRA, CALCULUS, KITTIES, TWOCATS, MATHWHIZ, SANDT, ILUVKEN

   Good passwords are unrelated single words that form a password students can visualize and remember. (PIZZACOLA, FOOTBOOK).

Operation Decode
Some possible strategies to break this cipher code include looking at spaces, puncturation, and double letters. Single letters are probably the letters A or I, the only single letter words in English. Students may list as many two-letter groups they can think of and then see whether they seem to fit anywhere (i.e., as, an, if, is, in, of, so, to). They may also first figure out the greeting and signature lines. The process includes trial-and-error substitution while looking for the sense of the message. The correct cipher code alphabet and decoded cipher follow.

By itself, the NOVA Decoder Ring can encrypt and decode simple cyphers, but as the students demonstrated, these ciphers are not highly secure. The same letters always substitute for each other.

But a more complex cipher is more secure because it requires more strategies to crack it. The cipher letters used to represent actual text change after each letter is encrypted.

Resources

Books

Hinsley, F.H., and Alan Stripp, editors. "Codebreakers: The Inside Story of Bletchley Park." New York: Oxford University Press, 1994.
Provides a compilation of accounts by many of the leading codebreakers at Bletchley Park.

Kahn, David. "Seizing the Enigma: The Race to Break the German U-Boat Codes, 1939-1943." Boston: Houghton Mifflin Company, 1991.
Examines the history of the cracking of the naval Enigma and its impact on the U-boat war in the Atlantic.

Web Sites

NOVA Online -- Decoding Nazi Secrets
http://www.pbs.org/nova/decoding/
Includes an article describing how the Enigma machine works, insights into the minds of the Engima codebreakers, a feature on how encryption affects people on the World Wide Web today, and an interactive game that allows students to encode their own messages, e-mail them to a friend, and then have the messages decoded.

Bletchley Park
http://www.cranfield.ac.uk/ccc/bpark/morebpark.htm
Describes the work at Bletchley Park, contains links to other sites with information on Bletchley Park including a "virtual Enigma" to type personal coded messages (Java-enabled browser required).

Standards

The Operation Decode activity aligns with the following National Science Education Standards:

Grades 5-8 | Grades 9-12

Science Standard G: History and Nature of Science Science as a human endeavor Women and men of various social and ethnic backgrounds -- and with diverse interests, talents, qualities, and motivations -- engage in the activities of science, engineering, and related fields such as the health professions. Some scientists work in teams, and some work alone, but all communicate extensively with others. Science requires different abilities, depending on such factors as the field of study and type of inquiry. Science is very much a human endeavor, and the work of science relies on basic human qualities, such as reasoning, insight, energy, skill, and creativity -- as well as on scientific habits of mind, such as intellectual honesty, tolerance of ambiguity, skepticism, and openness to new ideas.

Grades 9-12

Science Standard G: History and Nature of Science Science as a human endeavor Individuals and teams have contributed and will continue to contribute to the scientific enterprise. Doing science or engineering can be as simple as an individual conducting field studies or as complex as hundreds of people working on a major scientific question or technological problem. Pursuing science as a career or as a hobby can be both fascinating and intellectually rewarding.