This study examined practices of teachers in Wake County Public Schools (WCPSS) high school Algebra I classes. Regression analyses of standardized state testing results allowed for identification of the most effective and least effective Algebra I teachers and schools. The study used surveys, observations, and focus group interviews to compare and contrast most effective teachers with less effective teachers. It found that the most effective algebra teachers averaged 68% of their time on new material daily; averaged seven transitions in ninety minutes; used sustaining feedback; had structured classes with a culture of mutual respect; told their students what to expect on tests and cautioned them about possible errors; emphasized problem solving and processes; and exhibited a sense of humor. These results can be used to motivate teacher and school improvement efforts.