This dissertation consists of an investigation of the theoretical perspectives, research findings, teaching materials and practices relating to the development of mathematical understandings and skills in time and fractions for junior primary children, specifically Year 3, with learning difficulties who remain in the regular classroom situation. As a result of this investigation an attempt was made to design improved concrete materials or manipulatives for use in the teaching of time and fractions and to devise recommendations for their appropriate use. The practical outcome achieved with these materials in one Year 3 class is also reported.