The world is noisy place, and errors can occur whenever information is stored or transmitted. Error detection techniques add extra parity bits to data to determine when errors have occurred.
This activity is a magic trick which most audiences find intriguing. In the trick the demonstrator is "magically" able to figure which one out of dozens of cards has been turned over, using the same methods that computers use to figure out if an error has occurred in data storage.
The ISBN example in the books uses the ISBN-10 code. A new code, ISBN-13, started use on 1 January 2007. ISBN-13 also uses a checksum, but has a simpler formula. For details, see the Wikipedia article on ISBN
Curriculum Links
The parity trick is a good exercise in mental arithmetic, and illustrates an interesting use of odd and even numbers.
It can also lead to discussion of the different ways that technology can fail. Parity-checking can prevent a small amount of random error, but it's powerless to prevent many kinds of human or systematic error.
Use a range of counting, grouping, and equal-sharing strategies with whole numbers and fractions.
Mathematics Level 1: Equations and expressions
Communicate and explain counting, grouping, and equal-sharing strategies, using words, numbers, and pictures.
Technology Level 1: Characteristics of technology
Understand that technology is purposeful intervention through design.
Technology Level 1: Characteristics of technological outcomes
Understand that technological outcomes are products or systems developed by people and have a physical nature and a functional nature.
Technology Level 3: Technological systems
Understand that technological systems are represented by symbolic language tools and understand the role played by the black box in technological systems.
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