This site requires JavaScript, please enable it in your browser!
Greenfoot back

Greenfoot - CS Unplugged

CS Unplugged is a series of activities for teaching computing concepts without computers. This can make the content easier to teach to young audiences. You can see their site here.

Greenfoot also aims to make learning about computers more intuitive and accessable, so it makes to see if these two could be brought together. This page is about that; building a series of scenarios that help to bridge the gap between CS Unplugged activities and Greenfoot.


The first set of activities built are made as a direct port of the equivalent CS Unplugged activity. Most of the activities involve multiple kids or direct interaction with teachers in order to display the concept being taught. So with the examples below Greenfoot has been used as a substitute where the activity is now as a scenario that plays out on screen or an interactive game.

Each example tries to closely follow a particular CS Unplugged worksheet. As such they also require no programming from the user.

Binary Numbers

This activity is for teaching how position can be used to represent different values within binary numbers. In this case the value of each bit is represented by a card, with the total value of all cards being the total value of the equivalent integer.

To make this more interesting the player is given values which they need to match using their cards, with the option of seeing the answer if they are unable to think up the solution.


The CS Unplugged activity for this can be found here.

Fax Machine

This activity is about teaching one way of representing images. In case it is by listing the number of black and white pixels on each line in turn, which is used by fax machines.

The player is given lists of numbers next to each line on a grid. Like a fax machine, they must decode these in order to correctly paint the appropriate image. This also includes multiple layouts which they can switch to.


The CS Unplugged activity for this can be found here.

Treasure Island

An implementation of a finite state machine. Each island represents a node in a graph where there are two nodes the user can make to get to another node.

Players are to work out the correct path from the starting island to the treasure island by choosing which path the plane should take at each island it reaches. This allows them to see the idea of moving from one state to another, like in a finite state machine.


The CS Unplugged activity for this can be found here.

Sort Grid

An efficient sorting algorithm where values are sorted as they move from one side of the grid to the other. Unlike the others this scenario is not interactive, instead being purely visual.


The CS Unplugged activity for this can be found here.


The next challenge was to then move these further into becomming programming exercises. This was mainly achieved by remove parts of functionality from the original set of activities which the user then has to implement themselves by following a worksheet. The main challenge with this step is to build programming challenges that reflect the related CS Unplugged activity.

These activities, including their associated worksheets, are available from the Greenroom.