This study reports on an investigation into the relative effectiveness of using two different constructivist approaches, namely dialectic and endogenous, in the teaching of everyday physics to students who are classified as having mild learning difficulties. The study was concerned with developing conceptual understandings in Physics starting with the learners idiosyncratic and individual conceptions and with monitoring the process of conceptual change as opportunities for the discovery of problem solving strategies were provided using a set of prescribed procedures. The study was ultimately concerned with identifying which of these two constructivist approaches might be more appropriate for teaching science to children in this category. The study identified and characterised two forms of teacher behaviour corresponding to the endogenous and dialectic constructivist approaches and data was collected during the course of a program of interventions characterised by these two approaches. Indicators to monitor and arbitrarily measure the process of conceptual change teaching were developed for use during the course of these interventions. It was the intention of this study to develop and implement two different instructional procedures and sets of materials which exemplified the two distinct constructivist approaches mentioned above. It attempted to evaluate the relative effectiveness of the impact of each program on the development of physics concepts in the sample and to establish whether a constructivist approach to science teaching is appropriate for students falling within the category of 'mildly intellectually disabled', and if so, which of the two approaches was most effective. Data demonstrated that these two approaches can each promote meaningful conceptual change learning and that short term memory attention deficits normally associated with these children did not seem to interfere with either the process or the outcomes of the interventions. There was evidence of conceptual transfer as well as active learning throughout the course of the research in both approaches and significantly this occurred in a study of Physics, a discipline in which even regular students have tended to exhibit a high level of passivity.