In order to discuss how productivity in education might be improved, we must first measure where it stands. The U.S. Bureau of Labor Statistics reports productivity statistics for private sector industries, but not for education, leaving various researchers to attempt such calculations using various inputs and outputs. This paper explores existing productivity measures in the private sector, and how these might be applied to education. It then uses examples of possible education productivity measures for the United States to explore education productivity trends over time and possible explanations for these trends. Across alternative measures, productivity in K-12 education has fallen for four decades.