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Session 6 - Error Detection and Correction

The purpose of session 6 is to introduce you to how computers detect errors in data and where the error occurs. It will introduce you to the idea of parity bits and parity check to determine if the data has been corrupted. This session requires the use of a pack of cards or cards with a colour on one side.

If you do not have any playing cards, then you need to make 36 cards from paper. One side can stay white and the other side needs to have a colour. All cards need to be the same colour (this can just be a coloured dot; the whole card does not have to be coloured in).

  1. Open the Card Trick  document and read page 2. This shows what is going to be done but does not explain how the trick is performed. See if you can follow it. Then look at the instructions below. Practice the trick yourself and then when confident do it with another person as in the magic trick at the start of page 2.
  2. Work through the extension tasks and see if you can make it work with other items and with odd parity instead of even parity used in the previous version of the trick.
  3. Go to page 3 and read through how ISBN numbers on books also make use of parity bits. Work through the example on the page and then get a book of your own and try it out. Go to page 4 and follow the instructions regarding ISBN numbers, what parity bits can you find? Answer the questions at the end of the page.
  4. Finally read the reason why we do this on the final page of the document.

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