The recent decades have seen an increased focus on improving early science education. Goals include helping young children learn about pertinent concepts in science, and fostering early scientific reasoning and inquiry skills (e.g., NRC 2007, 2012, 2015). However, there is still much to learn about what constitutes appropriate frameworks that blend science education with developmentally appropriate learning environments. An important goal for the construction of early science is a better understanding of appropriate learning experiences and expectations for preschool children. This dissertation examines some of these concerns by focusing on three dimensions of science learning in the preschool classroom: (1) the learner; (2) instructional tools and pedagogy; and (3) the social context of learning with peers. In terms of the learner, the dissertation examines some dimensions of preschool children's scientific reasoning skills in the context of potentially relevant, developing general reasoning abilities. As young children undergo rapid cognitive changes during the preschool years, it is important to explore how these may influence scientific thinking. Two features of cognitive functioning have been carefully studied: (1) the demonstration of an epistemic awareness through an emerging theory of mind, and (2) the rapid improvement in executive functioning capacity. Both continue to develop through childhood and adolescence, but changes in early childhood are especially striking and have been neglected as regards their potential role in scientific thinking. The question is whether such skills relate to young children's capacity for scientific thinking. Another goal was to determine whether simple physics diagrams serve as effective instructional tools in supporting preschool children's scientific thinking. Specifically, in activities involving predicting and checking in scientific contexts, the question is whether such diagrams facilitate children's ability to accurately recall initial predictions, as well as discriminate between the outcome of a scientific manipulation and their original predictions (i.e., to determine whether one's predictions were confirmed). Finally, this dissertation also explores the social context of learning science with peers in the preschool classroom. Due to little prior research in this area, it is currently unclear whether and how preschool children may benefit from working with peers on science activities in the classroom. This work aims to examine preschoolers' collaboration on a science learning activity, as well as the developmental function for such collaborative skills over the preschool years. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]