In full-sized form, the Syllabubbles would be a diagram occupying a piece of paper more than a two square metres in size; this is the version used for students to track their own progress. Blank bubbles are small topics that are not important enough to show up on a diagram of this scale. The rules for using the syllabubbles are simple:

• Complete bubbles working "outwards" from the first bubble, which is surrounded by a dark ring
• You cannot move onto a bubble unless you have completed all of the bubbles leading to it previously.

Syllabubbles are an obvious concept -- essentially, they are a mind-map of somebody who knows a reasonable amount about modern computers, namely me -- but in a teaching environment they are surprisingly useful. If you're clever, you can also take a look at the full version in its original MS Publisher 98 format, or as a really huge postscript file -- at least, publisher claims it's postscript. And of course, if you want a different format or a different version, just get in touch.