The editors of "Practical Application of Research (PAR)," a newsletter of Phi Delta Kappa's Center on Evaluation, Development, and Research, reviewed all of the research done since 1971 on the subject of instructional clarity. Instructional clarity was defined as the interaction between what a teacher does or says and the student's perception of that behavior. This summary of the PAR findings lists 11 specific behaviors of elementary teachers with good instructional clarity that were identified by students. The behaviors include making sure that explanations are clear and understood, providing adequate practice time, synthesizing ideas and demonstrating relevancy, adjusting teaching to the learner and continuously monitoring students, emphasizing important ideas, and demonstrating a high degree of verbal fluency. For teachers who want to increase their instructional clarity, it is suggested that they tape-record and analyze their instructions for a lesson. Four impediments to instructional clarity are described: fillers; vague or garbled instructions; inaudible pitch; and mazes (combinations of the three previous impediments). Examples are provided of the right way and the wrong way to introduce a lesson. (DC)