The HIV/AIDS tree assembling game was conceived by Joseph Kizito Bada in connection with his doctoral thesis (UEF, 2013): Integrating digital learning objects for HIV/AIDS prevention - a contextualized approach. Bada's objective was to test a student's understanding/recollection of information about HIV/AIDS that had been presented to them in a course unit. To succeed in the game, the student has to make the correct association between a list of 24 items and six categories. The details of this association are set out by Bada in this document.

A tkeden implementation based on Bada's game conception was developed in collaboration with Beynon in 2009.

To test out the game on a Windows or Mac platform:

1. Download the appropriate version of tkeden-1.73 from the Software/EDEN subpage of the EM Webpage.
2. Download a version of the game from here.
3. Unzip the file aids-hiv-game.zip and place the extracted folder v2 onto your Desktop (or to a new folder you create).
4. Run the tkeden interpreter, and select File/Open from the File tab on the 'tkeden 1.73 Input' window.
5. In the 'tkeden: Open' window
   • navigate to the Desktop (or to your new folder) and select the folder v2
   • Double-click on the file Run.e to bring the contents of the run file into the tkeden Input Window.
6. Press the 'Accept' button.

A screenshot of the game interface is shown below:

To play the game, you press the New Game button, and drag-and-drop the items labelled a-z into the segments of the circle labelled A-C to indicate how you think each item is associated with a category.

The colour convention for the window in which you drag-and-drop items, initially persistent white-on-black, will change as the game proceeds. When the matching of items to categories is successfully completed, the colour convention will be persistent black-on-white. En route to the solution, the colour convention will cycle through several different combinations until, on solution, it finally becomes stable.

The New Game button sets up a new random association between the letters a-x and the list of items. The Reset button allows you to start again without changing this association. There are two counters below these buttons. The red counter records the time taken to reach the correct solution in seconds. The blue counter registers a score (maximum 24) based on the number of correct associations established in the course of the game.

There is an auxiliary interface through which the steps taken to reach a solution can be replayed in different ways. Information about the learner's interactions are recorded in relational tables that can be accessed via the %eddi interface in the tkeden Input Window.

The implementation of Bada's game illustrates the distinctive bricolage-style of construction that is quite characteristic of EM. The core drag-and-drop mechanism was created by adapting a tkeden version of the dependency modelling tool that was the subject of a CS405 lab devised by Harfield and Care in 2006-7. The replay mechanism also borrows from Harfield, who initially developed interfaces to replay interactions with Sudoku solving construals.

The core observables that store the key semantic data for the game are categories and nodes. As can be seen from the display, there is a spelling error in the specification of the categories A-E in this version of the game: this can be corrected by revising the definition of the categories observable. It would be relatively easy to adapt the construal so that it is based on other associations from another domain. Unless the number of categories and items is unchanged, other observables would need to be redefined. For instance, there might have to be a different number of segments in the circular region in general, and this would affect the definition of the function computeclass() and all the observables associated with the category labels A-E.