A review of the possibilities and challenges of computer-assisted instruction (CAI), and a brief history of CAI projects at Stanford serve to give the reader the context of the particular program described and analyzed in this book. The 1965-66 arithmetic drill-and-practice program is described, summarizing the curriculum and project operation. An edited version of the daily log of the project operation documents the types of problems encountered in the first application of a new technology in an operational setting. The results of surveys of students, parents, and teachers at the school made after the drill program had been in operation several months are presented and discussed. Previous research on methods of arithmetic teaching is reviewed; the implications of this research for the design and content of the drill program are described. The report presents some models for student performance in considerable detail. A controlled experiment conducted within the drill program is reported. The hardware, programing logic, and programing language developed to handle the program are described and analyzed. Appendixes provide a report on the previous year's program in CAI mathematics and several examples of the set of drills used by students at various grade levels. (JY)