This paper examines educational environments that promote learning and explores the ways that such environments produce differentially positive results. It is based on a study that investigated the effects of a theoretically based social-constructivist approach to education, in contrast to the more classroom-based "abstract" instruction used in middle-school environments. Ten middle-school teachers participated in the study. The teachers met over the summer and designed service-learning projects in which they wanted to be involved and in which they thought students would be interested. The teachers reported that project-based instruction afforded an opportunity for students to succeed where they might not have in a traditional classroom. Teachers learned personal things about students, how students approached tasks, students' level of understanding, and students' existing knowledge about the content areas of the school curriculum. The results show that students who were involved in projects achieved higher gains in standardized test scores than did students in the control group, despite 20 percent less academic instructional time, suggesting that student involvement in projects during the school day enhanced their performance. Students who were already achieving at high levels also benefited from the project. (Contains two tables of data and four references.) (RJM)