This might involve giving concrete examples, different view-points, diagrams, models, anecdotes, and varying the level of detail. Some students should be encouraged to take the ESL subjects. Generally provision of these aids depends on student initiative. Their availability should be promoted in student handouts and on the Web. The answer to this question will vary from subject to subject.
Cost is a factor.
Another factor is the extent to which the textbook material overlaps the subject content being taught. It is difficult to use textbooks in lectures, as not all students are likely to buy them. However, references to the text for lecture material, or for additional material, can be quoted in lectures. Providing the textbook is cheap and readily available, examples can be set directly from the text. Any textbooks should be placed on Library reserve, and orders placed in advance from book stores.