One in four Americans have learned using Houghton Mifflin Harcourt School Division programs, which include science, reading, language arts, mathematics, and social studies for grades K-8, as well as an integrated pre-K curriculum, reading and math intervention, and professional development. The Houghton Mifflin School Division merged with Harcourt School Publishers in 2007 and today is one of the largest educational publishing houses in the US.