The central purpose of this study was to evaluate the effectiveness of an instructional unit on sustainable agriculture using a computer program as a tool to increase environmental awareness, enhance understanding of environmental problems, and promote the resolution of environmental issues in educational settings. The effectiveness of the unit was measured in students' knowledge of sustainable agriculture and both students' and teachers' ratings of the materials contained within the instructional unit;An experimental pretest-posttest design was used in this study. Sixteen Iowa schools (172 students) with agriculture departments who had expressed an interest in field testing the instructional unit were randomly selected. One-half of the teachers received the instructional unit during a workshop, whereas the other one-half received their instructional unit by direct mail;The findings revealed that the Sustainable Agriculture Manager (SAM) instructional unit was effective in increasing student knowledge of sustainable agriculture and environmental concepts. Analyses of pretest and posttest scores revealed that students significantly increased posttest scores on sustainable agriculture knowledge. Male students scored significantly higher than female students, farm students scored significantly higher than students living in the city, and high academic achievement students scored significantly higher than low academic achievement students. Low academic achievement students improved their posttest score with a greater difference than medium academic achievement students, and comparable to high academic students;General comments from the students indicated that the computer program was fun, made learning easy, and that the written materials and computer program were easy to understand and use. Teacher comments indicated that the materials were well received by all who used it, and competition was high among students during the completion of the SAM computer program.