The purpose of this study was to explore the nature of explanations used by science teachers in junior high school classrooms. Studies on explanation in education, philosophy of science, and everyday discourse were consulted. Twenty public school teachers participated in the study. The analysis was based on observations of 40 class periods during which the classroom discourse was audiotaped and later transcribed. Using the constant comparative method in analyzing the transcripts, 10 types of explanations were generated. These explanations were labeled analogical, anthropomorphic, functional, genetic, mechanical, metaphysical, practical, rational, tautological, and teleological. These 10 types were conceptually related to one another by subsuming them under more encompassing literature-based categories.