This study examined the relationship between observable teacher characteristics and productivity as measured by an increase in student achievement on a standardized test using a value-added approach. This analysis focused on teachers of algebra, geometry, and 11th grade English Language Arts in Arkansas. The authors generated a value-added score at the school-course level and attributed that score to each teacher of that course in the school. The authors then regressed observable teacher characteristics on the value-added measure. The authors found no evidence that teacher certification route affects student tests scores, but found that higher ability math teachers do lead to higher scores.