THE PURPOSE OF THIS STUDY WAS THE DEVELOPMENT OF INSTRUCTIONAL MATERIALS AS PHASE ONE OF THE DEVELOPMENT OF AN INSERVICE TRAINING PROGRAM FOR ELEMENTARY SCHOOL TEACHERS IN THE USE OF A PROCESS APPROACH TO SCIENCE INSTRUCTION. THIS APPROACH ALLOWS THE CHILD TO LEARN THE CONTENT OF SCIENCE KNOWLEDGE THROUGH THE PRACTICE OF SCIENCE BY USING THE SAME PROCESSES OF INVESTIGATION AND DRAWING OF CONCLUSIONS THAT ARE USED BY SCIENTISTS. THE FOUR OBJECTIVES IN THE DEVELOPMENT OF THE INSERVICE TRAINING PROGRAM WERE (1) PREPARATION OF A RATIONALE FOR A PROCESS APPROACH TO SCIENCE INSTRUCTION OF CHILDREN, (2) IDENTIFICATION OF A CONCEPTUAL FRAMEWORK TO GUIDE SELECTION OF SPECIFIC SCIENCE EXPERIENCES FOR CHILDREN, (3) PREPARATION OF INSTRUCTIONAL MATERIALS, AND (4) IDENTIFICATION OF THE SCIENCE BACKGROUND NEEDED BY ELEMENTARY TEACHERS WHO WILL USE THE INSTRUCTIONAL MATERIALS. FULFILLMENT OF THESE OBJECTIVES RESULTED IN COMPLETION OF A SET OF TEXTS FOR GRADES K THROUGH 6 (INCLUDING GUIDE MATERIALS FOR TEACHERS) BASED ON THE ELEMENTARY SCIENCE PROJECT OF THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. THE TEXTS WERE USED IN AN EXPERIMENTAL TRYOUT DURING 1964-65 IN THE PUBLIC SCHOOLS OF AUSTIN, TEXAS. (AL)