The Sorting Network
The larger island contains a parallel sorting network, which has become a quintessential activity from the free “Computer Science Unplugged” resource, which was developed by Tim Bell (at UC) and Mike Fellows.
The white paving stones represent nodes in the network, which should be linked using the lines shown in the diagram below (we usually draw them with chalk when using the network). It can be used to sort six values (numbers, dates, words or even musical pitches) by having six people stand on the six paving stones at the north end of the garden, and follow the lines until they meet someone at a double paving stone. The person with the smaller number goes to the left, and the larger to the right. Eventually the six should arrive at the southern end sorted into order. A more detailed explanation of this can be found at the Computer Science Unplugged web site.
A sorting network