This digest provides an overview of several meta-analysis studies which focused on various aspects of science instruction. These studies examined: productive factors in science learning for grades 6 through 12; quality and quantity of instruction; effects of various teaching strategies on science achievement; instructional systems in science education; inquiry teaching and advance organizers; and other areas. Some possible generalizations from these studies are included. For example, it is noted that instructional techniques which help students focus on learning (preinstructional strategies, increased structure in the verbal content of materials, use of concrete objects or realism) are effective in promoting student achievement in science. (DH)