The Silent Period is an idea stemming from Krashen's Input Hypothesis that learners in the earliest stages of language learning need a time when they just listen to and assimilate the target language, before they are ready to produce it.
Krashen states ‘It has often been noted that children acquiring a second language in a natural, informal linguistic environment, may say very little for several months following their first exposure to the second language’. (1987:26) and ‘the child is building up competence in the second language by listening, by understanding the language ... speaking ability emerges on its own after enough competence has been developed by listening and understanding’ (ibid.: 27).
In methodologies that adopt a Silent Period - such as Total Physical Response - this is extended to adult learners. In TPR, for example, for the first 60 hours of the language course the learners are not required to say anything, just to listen and understand, and then demonstrate their understanding with some sort of physical action. Activities like Describe and Draw and Describe and Arrange, though with the teacher giving the descriptions rather than using the activity as an information gap exercise, would fit neatly into this type of approach.
However, there is no conclusive evidence that the silent period is useful in promoting acquisition. As Ellis points out : ‘There is some disagreement regarding the contribution that the silent period makes to language learning’ (2008: 74), and some learners may, on the contrary feel frustrated by the approach.
References
Krashen, S.D. (1987) Principles and Practice in Second Language Acquisition, Hemel Hempstead: Prentice Hall.
Ellis, R. (2008) The Study of Second Language Acquisition (2nd edition), Oxford: Oxford University Press.