DI designers test the programs carefully before publishing them, just as aeronautic engineers test airplanes before marketing them. Each DI program is extensively revised, based on specific student error data from the field test. Scripting the lessons allowed sharing of these polished stones across teachers. Also scripting helped reduce the amount of teacher talk. According to Engelmann s theory, children learn by working through the sequence of tasks with carefully timed comments from the teacher.
Children learn little from straight teacher talk.
Too much teacher talk decreases pupil-motivation, draws out lesson length unnecessarily, and often causes confusion by changing the focus of the tasks, disrupting the development of the larger generalization, of which a teacher is usually unaware when first teaching a program. Even though the programs are carefully tested and scripted, successful use of them requires training in the special techniques of delivery. Teachers must make many decisions in response to the children s performance. Some of the most important decisions involve placing each child appropriately and moving the children through the lessons at a pace that maximizes their learning potential. The scripted presentations are part of the whole lesson, and the DI lessons are part of the whole school day.