On the other hand, teachers come into the classroom with their own construction and conceptions of subject content, and according to Patrick (1988), are not 'neutral'. Therefore, a teacher's understanding can colour the students understanding, and together, Patrick (1998) and Marton and Booth (1997) suggested that some teachers 'moulded' the students' construction of a concept to align with their concept interpretation. Einsworth and Collins (2002) conclude that the form of understanding impressed onto students is largely dependent on the teacher's personal interpretation of the subject content. Therefore, although the constructivist theory assumes that the construction of understanding is the product of the learner's interpretation exclusively, the constructivist theory does not account for the interplay between teachers' and learners' comprehension.To accommodate these pre-requisites of learning, the individual's knowledge needs to be continually assessed. As a regular classroom practice, formative assessment could be used as a regular approach to assess existing and new understanding, before moving to the next lesson. Formative assessment is a regular, informal mode of assessment, allowing teachers to monitor students' progress, gain an appreciation of what has been learnt and adapt their teaching practices to optimise further learning (Black and Wiliam, 1998). Accordingly, given that learning is an active and evolving processes, formative assessment can be used by teachers to assess, monitor, challenge unclear perspectives and adapt classroom practices to accommodate the constructivist principles of learning. Therefore, it is reasonable to believe that constructivist approaches to learning favour the use of formative assessment and may prompt its use in the classrooms, which Atkin et al, (2001) reports as being very valuable.