This publication examines the role of the science teacher, and how the teacher brings to his work substance, structure, and style. The substance of science and technology consists of two elements: its products, the conceptual schemes and tools which give scientists and laymen their comprehension of the world; and the processes which enable scientists to fashion their concepts of the way the world works. Style in science teaching consists of what the teacher does and the way he does it as he develops an environment in which the children may learn the nature of the material universe, by seeking explanations which are orderly for the particular and special moment of their development and their idiosyncratic ways of learning, and by testing their explanations, that is, seeking empirical validations of their assertions. Structure includes content ordered in the form of concepts; these concepts are ordered further by the contributing experiences which children bring to the school and the school brings to the children. A structure is provided for the elementary school science curriculum in the form of conceptual schemes and concept levels. Also provided is a structure for the junior high school science curriculum, which is organized around the concepts of life, matter and energy. (Author/MLH)