You'll see that in the bottom left of the above screen image there are two option buttons: "Words" or "Sentences"
"Words" means that the text is divided in roughly equal-sized chunks based on the number of words. This has been the default setting until now, and it tends to create activities where:
- each chunk of text is roughly equal in size
- text chunks pay no attention to full stops or line breaks
Text-reconstruction of this kind forces the reader to look out for context clues such as grammar, word order, verb / adjective agreement, as well as the actual meaning of what they are reading. On the one hand, this type of activity can be challenging because the student has to know how the words fit together grammatically, but on the other hand it could be seen as less challenging in terms of understanding of the flow of the text or story.
"Sentences" means that textivate will attempt to break the text up into chunks which take account of line breaks and full stops, where possible. Of course, many of the activities are constrained by the number of tiles on the screen, so you will find that if your text has fewer sentences than there are tiles on a particular screen, the longer sentences will be divided. Likewise, if your text has more sentences than there are tiles, the smaller sentences will be combined.
This option doesn't make the same demands on students in terms of grammar -- they are not spending as much time in mid-sentence looking for the correct word to continue the sentence. They are spending more of their time looking at the meanings of the sentences and working out their order within the text or story.
A tile activity divided by word chunks: