ion claimed by Bentley and Watts may be evidence of a more significant issue. Our belief is that the model of constructivism generally put forward is one which is based largely on methods which work for researchers rather than methods which work for teachers in typical classrooms. The discrepancy between the version put forward by researchers and the version applied in the classroom may therefore be indicative of a realistic response by teachers, who may be committed to a constructivist approach in principle but have to find ways of making this manageable in practice. We believe that a number of significant issues about how to make constructivism applicable to classrooms have not yet been addressed by the various research groups.
Issues relating to constructivist approaches to teaching and learning
One issue is that of the separation of the phases of the constructivist teaching and learning sequence. Although it is recognised that the elicitation phase may provoke learners to reconsider their thinking (Needham, 1987), the phases are generally described as separate and distinct (Driver and Oldham 1986; Needham, 1987; Scott, 1987). Teachers commonly perceive these phases as separate, and Nuffield Primary Science (1993b) suggests that teachers may have difficulty in switching from one phase to the other. Curriculum materials produced by Leeds (1992) describe how teachers will find it easier to plan activities after the learner's ideas have been identified. However as a model for teaching this separation is not helpful. The practicalities of timing and planning for teaching make this model, which works well as part of a research programme, very difficult to implement. The separation of the two phases also means that the purpose of the elicitation phase is only evident to the teacher and not to the learner.
Precisely how the learner's ideas can be taken into account in planning suitable restructuring activities is also a cause for concern. In principle the suggestion that teachers should plan activities on the basis of what the learner already knows and understands seems like an obvious way to proceed. The problem comes with the sheer practicality of attempting to do that with a class of 30 or even 40 or more pupils. Even if the teacher has adequate information about the learners' initial ideas, attempting to respond to their individual ideas can become an impossible exercise in classroom management. We know many teachers and student teachers who have made a commitment to a constructivist approach but feel guilty because they are unable to manage to implement this in their practice.
Guidance is readily available on the ideas which learners hold and on the range of methods which researchers have used to elicit the learners' ideas (Driver et al, 1985; White and Gunstone, 1992; Driver et al, 1994). However the guidance available to teachers on how to promote restructuring of the learners' ideas is much more limited. Claxton (1986) described the "mountain of examples of children's alternative conceptions" (p126) which were available at that time and noted that the guidance for teachers on how to restructure the learners' ideas was less prominent in the literature. The balance in more recent research remains weighted towards elicitation rather than restructuring, and the comments made by Claxton have been reiterated by Trumper (1990), White (1994) and Prideaux (1995). Research into the ideas that learners hold is relatively "safe" research, in that it is located within a well-documented paradigm, it is easy to manage, and it is very difficult to challenge since it makes no attempt to predict or to prescribe what practice will be effective. By contrast research into how to restructure the learners' ideas has few advantages, even though it may be more valuable for teachers.
Underpinning these concerns is the issue of the relevance of the research to teachers. There seems to be little doubt that researchers frequently are concerned about the classroom relevance of their research. For example, Driver and Oldham (1986) make it clear th