To do this, first create your user-defined gap-fill by clicking on the button on the textivate home page:
Then close the user-defined gap-fill edit box. This adds [#] in front of the words (or groups of words) that you have selected as gaps.
Then type your clue or prompt after the # on the textivate edit screen (in the "Text" box or the "Show all" box), like this:
[#your clue here]the_gapped_word
You might end up with a text that looks something like this:
(note that I've put the clues in capitals, but you don't have to do this)
N.B. Clues / prompts only appear when the word list is not displayed.
You can choose to hide the word list on the activity screen itself, by clicking on the "Hide words" button.
Or if you want to link to an activity or embed it somewhere else, you can tweak the activity url. See this blog post about fine-tuning your URLs.
(You can also select to hide the word list if using the gap-fill as part of a sequence.)
Here is a link to the gap-fill from the image above, with the word list hidden (and autocorrect off): http://www.textivate.com/udgapfill-w0ljn1e00
And here is the same activity embedded, this time with autocorrect on:
Adding clues / prompts to gap-fill activities adds a whole new dimension. It's great for TRANSFORMATION activities where a prompt is supplied and the student has to modify the word or include something from the same word family according to the specific context.
And of course, you can print worksheets with this new feature too.
Here's a worksheet of the above text: