This is a nice little starter to get students thinking about error correction and to demonstrate how parity works to locate errors. First download the html file (at the bottom of this post) and open it to show a blank colour grid as shown to the right. I normally have this on the board when students enter the room and ask them what they think it is and how it might relate to Computer Science |

The teacher can make the choice of how their parity information works, they can either choose

**ODD**or

**EVEN**parity so that the total number of Blues is even or the total number of Reds is even in each line.

See the example below where I have used even Parity, I focussed on the blue squares to make sure each line (horizontal and vertical) has an even number of blue squares via adding the extra parity bits:

There are also possible extension questions:

- If there is an error like this, should the receiving computer just fix the problem anyway (as that computer knows exactly what the error is)?
- What would happen if there are two (or more) errors in the data sent?

For other ideas for teaching in general or specifically teaching aspects of Computer Science / ICT and Business, click here.

The HTML file can be downloaded below:

lr_paritybitsdemo.html |

I have made some slight modifications to the code just to make it fit better on the screen of me when I am teaching without have to zoom in too much.