IntroductionAn understanding of classroom learning requires careful analyses of the variables that constitute the learning environment. Among those that are most likely to influence learning are teacher and pupil discourse since verbal interaction is the principle mode of communication in most classrooms. For example, through the use of appropriate questions, teachers can provide pupils with a cognitive focus on the instructional objectives. Similarly, a clear explanation in response to a pupil question can clarify misunderstandings that might otherwise inhibit learning. Thus, the quality of the verbal interaction may directly affect the amount of learning that occurs. Although much of the research on verbal interaction has dealt with aspects of teacher questioning, the results have tended to be inconsistent (cf. Winne 1979). In contrast, a variable called wait-time, which is related to the duration of certain pauses between speakers, has been shown to have a consistent effect on the quality of verbal interaction in classrooms.If teacher discourse is to influence pupil learning, the information contained in the discourse must be cognitively processed by the learner. As a consequence, the rate at which information is presented should be matched with the cognitive processing capabilities of pupils. Cognitive processing of data is likely to be dependent on learner attributes such as cognitive aptitude and motivation state, as well as characteristics of the discourse. For example, processing time for cognitively complex discourse is expected to be greater than the time required to process less complex verbal information. Thus, as teachers provide pupils with information or provide a cognitive focus through soliciting, adequate time should be provided for all pupils to engage in an appropriate manner. To ensure that adequate time is provided, teachers should pause after solicitations or at regular intervals during explanations.The pause following pupil discourse is also of potential importance. As Rowe (1974 a) noted, speech is interspersed with pauses which range from quite short time intervals separating individual words to much longer intervals which occur as a speaker completes a segment of speech and pauses to consider what to say next. These time intervals often exceed three to five seconds. Siegman and Pope (1965) reported that the length of pauses in discourse increased in proportion to the difficulty of the task, whilst