The Life of Fred math series is a complete set of math books written by Dr. Stanley Schmidt that cover everything from basic first-grade arithmetic all the way through university math and statistics. There's also a book on physics. It is popular amongst homeschoolers.
Life of Fred Elementary Series books can be rented at any time of the year. The rental period for the Elementary and Intermediate Series is 5 months (semester). All other LOF books are 10-month rentals.