The techniques used to collect data on the dominant speech patterns and verbal expressions of elementary school children are described as a means of systematizing oral language instruction. Specific recurring errors discovered in children's communication are discussed: the failure to focus on a major point, to support ideas, and to clarify questions; the inability to differentiate between ideas or to subordinate one idea to another; a lack of adequate description; and the tendency to use a stereotyped vocabulary. It is proposed that these errors can be diagnosed and treated in the classroom through the use of small instructional groups, audiovisual devices, and experience charts. (JB)