This study was carried out to examine the relationship between instructional materials and delivery of pre-primary science curriculum in Naivasha Sub County, Nakuru County, Kenya. Despite the fact that many scholars have conducted extensive studies on educational practices and outcomes, the performance of science in Kenyan schools has continued to be deplorable. The researcher therefore, aimed at exploring the link between instructional materials and science curriculum delivery. The objectives of this study were to find out types of science instructional materials available in pre-primary schools, establish the extent to which science instructional materials are used in pre-primary schools and determine the relationship between availability and utilization of instructional materials and teaching of science in pre-primary schools. This study was guided by the Constructionist Learning Theory advanced by Papert (1980), which proposes that effective learning occurs when learners actively interact with concrete materials. The descriptive survey research design was used to shape the study on the relationship between variables under scrutiny. The study’s target population comprised pre-primary schools, pre-primary school teachers and pre-primary school learners. Stratified random sampling was used based on urban and rural pre-primary schools while simple random sampling method was used to select the study’s final sample comprising of 34 pre-primary schools, 66 teachers and 365 pre primary school children. A questionnaire was provided to the sampled teachers to collect primary data for the study.