As of 2016, popular Harcourt school science textbooks include the California Science and the HSP Science series of textbooks. Each series has books for kindergarten as well as for each grade level, from grades one to six. Houghton Mifflin Harcourt, a Boston-based educational and trade publisher, publishes Harcourt science textbooks.
The "California Science Grade 1" textbook has three units: physical science, life science and earth science. The physical science unit tackles topics such as the concept of mass and the different states of matter. The unit on life science discusses topics such as plants, animals and communities, while the earth science unit provides knowledge on weather systems, the water cycle and the earth's seasons. Harcourt also publishes textbooks in Spanish as Harcourt Ciencias. Additional online resources for students and teachers are available on the HMH website.