This is another activity that achieves something that doesn't seem possible - people who don't trust each other and can't see each other are able to agree on the outcome of a random coin flip.
This is an absorbing activity for an individual student or a whole classroom.
The Royal Institution UK and Microsoft Research together have produced activities in encryption, cryptography, and zero knowledge protocols for the classroom at the locations below:
Logic Circuit Builder applet from Johns Hopkins University lets you create your logic circuits and compute them to view the resulting input/output truth tables. You can view the truth tables for the common gate elements here
An online course in Digital Circuitry was developed for ThinkQuest by Montgomery Blair High School Magnet Program for Science, Mathematics, and Computer Science is at An Online DIGitAL Circuitry Course .
Robin Forry from the University of Cincinnati has an activity in desinging Integrated Circuits called Computer Chip Design where in the first activity students create a layout for a special purpose computer that uses mathematical functions to compute a target value given two inputs. There is also a second activity where students create a layout of components of a processor that minimizes area on the chip. This activity was developed for high school students.
Michael Wolf from the University of Cincinnati has an activity in Input, Output and Data Communications called LMR Communication where students learn about land mobile radios through experimenting with walkie-talkies for hands on learning of general radio functions. Then the students will learn about conventional and trunked queues. This activity was developed for high school students.
Do I.T. has logic gates tryout applets at Computer Logic
Hobart and William Smith Colleges has the xLogicCircuits Lab that explores logic circuits created out of AND, OR and NOT gates. The relationship between circuits and Boolean algebra is also covered.
Claude Shannon's Experiment to Calculate the Entropy of English is aimed at determining the entropy of an English letter (the amount of information in bits that we obtain on the average when we learn one letter of English).
Illuminations has an application that explains Cryptography at Codes . Cryptography is science that uses mathematics to encrypt and decrypt data.
Illuminations has an activity Arithme-Tic-Toc where students will be introduced to modular arithmetic by first examining a five-hour analog clock and its mathematical properties. Then students will investigate patterns and relationships that exist in 12-hour addition and multiplication clock tables.
University of California, San Diego Maths Department has applets that demonstrate concepts in Cryptography in the module Introduction To Cryptography .
Centre for Innovation in Mathematics Teaching has the following teaching packages developed to teach Codes and Ciphers in their Maths Curriculum:
University of Cambridge Caret has the Enigma Game which is an interactive code breaking game for ages 11-14 and 15-18 incorporating 4 levels of difficulty. Download the Enigma Activity PDF for more documentation.
Herong Yang has a free Cryptography Tutorials book which is a collection of notes and sample codes written by the author while he was learning cryptography technologies himself. It can be used as a tutorial guide for beginners.
Dr. Lisa N. Michaud has the following resources of interest:
Shodor Interactivate has the following resources in Ciphers and Codes that includes activities and explanations for learners and instructors with discussions:
Jim Loy has the following guides, notes and puzzles that can be used as ideas for classroom activities in Cryptography, Codes and Ciphers:
Simon Singh offers a page full of growing resources for teaching codes and code-breaking. These resources are organised to be offered on "Spy Days" where pupils can learn about these topics using lessons and activities that span over a day.
Spy Day Ideas and Lessons (developed for Year 9 pupils in the UK)
Cipher Challenge (developed for Years 5-8 pupils in the UK)
Code Challenge (developed for gifted children)
Teacher Packs (developed for Years 5,6, and 7 in the UK) / Key Stage 2/3
Senior Resources
See the entire set of resources with additional documentation at Teaching Resources .
The Enigma Project has a good demonstration section on the Enigma Machine. Watch the Video: James Grime Demonstrates the Enigma Machine . To discover more about the history of code breaking download the Code Book CD-ROM by Simon Singh and Nick Mee, and take the 5 challenges on the page.
SCOUTS, South Africa has a website dedicated to learning secret codes and how to use them at Codes for Cubs and Scouts . This site gives an gentle introduction to most codes with exercises to try out.
PBS' NOVA Online has the following resources available in codes and ciphers with worked out examples:
Decoding Nazi Secrets: a television broadcast from November 9, 1999 offers some materials for teacher use which based on the program. Please note that the video is not required for using these activities:
Melissa Salpietra has the following interactive online activities:
Stephen C Phillips has the following fun activities and resources on Morse Code:
SECRET CODE BREAKER is a comprehensive site covering a series of cryptography publications for young readers that provide detailed instructions explaining how to "crack" secret codes and ciphers for beginning cryptanalysts. Included are computer programs for code breaking and a series of coded secret messages actually sent by secret agents, spies and military commanders beginning with the Revolutionary War to the present including messages from the CIA "mole" Aldrich Ames to the KGB.
Frode Weierud has a collection of cipher machine simulators that can be downloaded for understanding how these machines work. For the complete list of simulators with sample screens and documentation please visit Enigma Variations: An Extended Family of Machines . These resources could be used for classroom tasks and teaching ideas at a senior school level.
Dirk Rijmenants has an entire website Cipher Machines and Cryptology with loads of resources in Cryptography. A great activity challenge of interest is the following challenge which could be used as teaching tools:
University of Southampton School of Mathematics has the National Cipher Challenge that offers the following teacher resources and materials:
GK-12 at Harvard University has some useful resources and worksheets in Encryption.
Description: Introduces students to some basic ciphers and the concept of encryption. Can be extended with a programming exercise in which one or both are implemented. Can also be extended with a discussion of public-key encryption works to provide the encryption we use online today. Note that the examples and problems given are best if they are customized to be phrases that are meaningful to the students in the class.
Center for Discrete Mathematics & Theoretical Computer Science at Rutgers University has the following relevant resources created by various high school teachers:
Purdue University's GK-12 has a lesson plan for teaching Caeser Ciphers: An Introduction to Cryptography
CSIRO's SCIENCE BY EMAIL has the following activities:
The Thomas Beale Cipher is a 10-minute award-winning film that tells the true legend of history's most challenging cipher. Professor White, cryptographer extraordinaire, is on the trail of the notoriously uncrackable Thomas Beale cipher—a century-old riddle hiding the location of a fortune in gold that has tormented its pursuers since inception. But White is not alone—shadowy forces are tight on his tail. The film contains 16 hidden messages that hold clues to the characters' secrets. Eight are fairly easy and require only a close eye. Six are moderately difficult using various encryption methods. Two are extremely difficult and will require a genius mind to decrypt.
Wolfram Demonstrations Project has the following demonstration activities. Note: You will need to install the Wolfram CDF Player in order to use these activities. You can either download each demonstration or use your browser to run it.
Count On has a complete section dedicated to Codebreaking with lots of online activities students can try in the following Ciphers and techniques:
Math Night has a module Secret Codes:
Mike Koss has the following resources:
BEYOND DISCOVERY has a great section on The Code War
National Security Agency (NSA) Cryptokids has a section meant for young children on Codes and Ciphers:
Jacob Mathai has a concise page on History of Computer Cryptography and Secrecy Systems
DIMACS, Rutgers University has the following sections for teaching Cryptography & Network Security at high school level:
White Haven Maths has an extensive section on Codes and Ciphers which features detailed explanations and tools for learning how each cipher works
Frank Speiss has a very well designed Enigma Machine Simulator using Flash with the Help File on how to use the simulator
GCHQ Challenge (Cheltenham Science Festival) has some of their code breaking challenges available for students to try out from various past years with solution pages for each:
Simon Singh has The Black Chamber , where you can learn about codes and codebreaking, encrypt your own messages, crack those of your enemies, and play with interactive enciphering programmes. The Black Chamber provides a brief history of cryptography from Ancient Rome to today's Information Age, and it is also a mini-tutorial in codes and codebreaking. If you want to know more, then a not-for-profit CD-ROM containing all the material in this website and lots more is available. It contains more sophisticated material (e.g., an Enigma emulator), advanced tools (RSA encryption), items that would not work over the Internet (animations of quantum cryptography), and notes for teachers. Listed below are the contents:
Abdullah Seddiq (MIT Blossoms) has The Magic Picture: Steganography in Bitmap Files , a video with teacher guides and other resources. This video aims to connect many topics in computer science to reach the writing of an application that can do something useful in actual life. The student will get to know the concept of ciphering and hiding (Steganography in bitmap files), will have a glance at the American Standard Code for Information Interchange table "ASCII", will understand the structure of bitmap (BMP), and learn how color is stored.
Monticello has the following resources on the Wheel Cipher:
Virtual Science Fair has a science fair project See the Unseen, Hear the Unheard - Exploring the Limits of Steganography