In the ESL teaching world there is currently a continuing debate as to which type of class materials for oral and listening activities is more suitable. The choices are between authentic dialogues and materials taken from authentic sources such as radio interviews, magazine articles etc. and scripted dialogues prepared especially for the lesson by the teacher or some other English teaching source. Generally, the argument for authentic materials is that the materials should represent what learners will be confronted with in every day life when using English. On the other hand, proponents of scripted materials feel that by preparing the material students are not introduced to issues that may be beyond the scope of the current level. Both arguments are equally valid, and it is my own practice to use both types of materials in my classes. Below is a consideration of what I consider the main advantages and disadvantages of both types of materials.
The advantages of authentic dialogues are probably mostly in the area of listening comprehension. By using authentic dialogues, learners are confronted with 'real life' experiences in which they will have to function. By using these authentic dialogues, the teacher can focus on variations in pronunciation, and how intonation and incomplete structures are used to express meaning. By having students focus on such areas of openings and closure, a teacher could then lead the class to discussion about, and practice of, appropriate types of openings and closure as well as other appropriate language (or inappropriate as the case may be). Other, more subtle issues, may also be addressed by using authentic dialogues. For an advanced class, the issue of flouting co-operative principles may be discussed by using the manner in which this is achieved in an authentic dialogue as an example. Students could then model oral activities on the exchange and see how close they can come to producing the same effect (a very difficult task indeed!)
I think that using scripted dialogues are probably most useful when a teacher is trying to focus on correct form. This is particularly appropriate when working towards stimulating oral work. By using a scripted dialogue, the teacher can steer the class towards new or recycled language skills while keeping irregularities to a minimum. Especially in the case of lower level classes, where communication skills are generally the primary target of such an activity, the use of a scripted dialogue allows the teacher to concentrate on 'bare-bone' structures without having to worry about confusing the students. The issue of shared knowledge does not need to be addressed, as well as other linguistic subtleties (such as flouting co-operative principles in order to express irony) and the teacher can use his/her knowledge of the class's ability to model the conversational flow.