Even when texts are long, only a small number of words meet the key criteria of being both uncommon and much repeated. For instance, in all 21,000 words of the simplified version of The Mayor of Casterbridge, we were able to identify only eight items that were both unusual enough to be unknown to the learners (i.e. not among the 2000 most frequent English words) and used in the text at least seven times. Other attempts to locate frequently occurring words resulted in lists consisting mostly of very common items: In our experiments with Dutch and German texts, we found that the set of items that occurred one time only in the texts was the most likely to contain unusual words that learners might not already know. .
Therefore, the question that L2 materials designers might usefully address is the following: What can be done to improve the chances that learners will get multiple exposures to new words when they read? One possible solution is rewriting texts to include more occurrences of items. However, there are distinct disadvantages to this approach. In addition to being enormously time consuming to do, rewriting does not allow learners to direct their own learning. The writer, rather than the learner, selects the few items that will receive the recycling treatment. Furthermore, as our brief venture in this direction showed, it is not at all clear that such contrived texts foster the expected learning results (see the Chapter 5). .
A variation on this approach is to supplement a text (instead of altering it) to increase numbers of encounters with selected items. For instance, Paribakht and Wesche (1997, 1999) tested the effects of reading texts and then completing supplementary vocabulary exercises that recycled certain items. They found the additional activities to be beneficial. But like the devising of special texts, this is an inefficient solution. The exercises are laborious to write, the number of words that get instructional treatment are necessarily limited, and it is the writer, not the reader, who sets the learning agenda .
