This report, the third in a series from the spring 1998 national survey, "Teaching, Learning, and Computing," focuses on how teachers have incorporated computers into their instructional practices. The study is comprised of completed questionnaire responses from teachers, principals, and school technology coordinators from 1,616 schools. Part 1 discusses teacher-directed student use of computers, including basic descriptive statistics, access to classroom computers, and computer platforms used by students. The extent and variety of software used and teachers' objectives for use are addressed in part 2, including types of software used, software that teachers judge as most valuable for students, patterns of software use, objectives for computer use, and student computer use for school work on their own time. Part 3 considers teacher computer expertise and professional use, including teacher professional use of software, and teacher self-reported expertise with computers. It was found that teachers who are the most technically knowledgeable about computers are the ones most likely to have students use computers in varied and complicated ways. At any level, the cluster of teachers strong in most aspects of computer use is small (5% of elementary school teachers, 4% of middle school teachers, and 13% of high school teachers). Although small in numbers, these teachers constitute the standard for instructional computer use, and their numbers are likely to increase in the near future. Data are presented in 24 tables throughout the report. Supplementary tables and a summary of study methodology are appended. (MES)