I'm a big fan of the Computer Science Unplugged website, which offers offline, kinaesthetic lessons for various computer science and information technology concepts - many of which feature topics that are on the ITGS syllabus. On its Activities Under Development page the site features an in-progress lesson plan called "The Defrag Game" which looks really promising. It aims to explain disk fragmentation and defragmentation using a series of coloured and numbered cards to represent different files (colours) and the disk sectors that make up those files (numbers). Disk defragmentation software falls under section 3.2 Software of the ITGS syllabus.
The cards can be used to help explain the concept to students, or alternatively students could be asked to read or research the concepts behind fragmentation and defragmentation and explain them back to the class or the teacher. The lesson difficulty can be changed by using larger 'files' (1-4 cards works well; 5 or 6 requires more careful placement to avoid fragmentation) or by adding more 'files' (additional colours).
The activity could be done using a few packets of playing cards or a few post it notes, but for a more permanent and better looking approach, I have created a set of cards which can be printed and lamented. You can download a PDF of the cards (featuring cards 1-6 in four different colours, plus free space cards), or you can download the original SVG file and make your own changes (Licence: CC-BY)