Reviewed are several pertinent research articles dealing with cognitive development, Piaget's theories, and science instruction, especially those that relate to procedures that can be implemented by classroom teachers. The research findings on developmental levels of Piaget discuss: (1) tasks that indicate a change from preoperational to concrete operational abilities and from concrete to formal operations; (2) science concepts and developmental levels; and (3) teaching and development. An outline of Piaget's stages of intellectual development is also included. (HM)