Teachers at the primary level should resume the neglected practice of diagnostic teaching. This means that the teacher should observe all aspects of a student's cognitive behavior in the teaching/learning act and then plan instructional strategies for subsequent lessons. Some significant cognitive behaviors observable in diagnostic teaching are students' auditory and visual attention and recall and their tracking and blending abilities. Students exhibiting deficiencies in these areas need additional tactile, kinesthetic, auditory, oral, and visual stimulation. Teaching principles and strategies teachers might use to supplement basal reader programs are: (1) emphasize listening, speaking, reading, tactile, and writing activities for students with poor visual recall; (2) introduce all new vocabulary in familiar printed and oral context for initial teaching; (3) insert visual clues (mnemonic aids) in reading materials; (4) teach each letter sound with one visual clue; (5) sequence and pace all tasks so that overlearning occurs for each one; (6) recognize the significiance of levels of cognitive development in students; and (7) encourage students to learn to read the language of formal written expression by listening to adult models. (FL)