*Hands-On Algebra, Frances Thompson, The Center for Applied Research in Education, Similar to Hands-On Math, but covering Pre-Algebra and Algebra topics. Excellent coverage of Algebra topics. This is the best book I have seen for explaining and demonstrating Algebra concepts physically and visually. Very smooth transition from Hands-On Math to Hands-On Algebra. Similarities of Algebraic computation and arithmetic computation are used throughout to assist the student in connecting earlier math work with Algebra. Again, a must-have in my opinion.
*Nimble with Numbers series, Leigh Childs and Laura Choate, Dale Seymour Publications, This series is published as overlapping two-grade books (Grades 1-2, 2-3....6-7) A brilliant series. This is another must-have in my opinion. Books includes short hands-on lesson/games, independent activities in a game/puzzle format, short quizzes to check progress, and games for two (or more) players. The games are designed to support concept development and mathematical thinking. These games facilitate practicing computation by repeating concept development rather than rote memorization. "Memorization" comes from continued use of the concepts during the games. Only computation topics are covered. This series is a fundamental component of my math program.
*Mathematical Reasoning Through Verbal Analysis (two book series), Warren Hill and Ronald Edwards, Critical Thinking Press & Software, An excellent series for developing mathematical thinking. This is a book of reproducible worksheets and so might be unsuitable for extreme unschoolers. Most worksheets are short and require mathematical thinking rather than rote memorization. A valuable supplement to any math program.
**Note: The books in this section are the core of my unschool math program. I use Hands-On... to learn how to demonstrate math concepts, but I do not work directly from the book. I use Nimble with Numbers to practice computation and mathematical thinking, and to introduce or reinforce math concepts. I rarely need Mathematical Reasoning for my own child, but have needed for most kids I`ve tutored. Hands-On... and Nimble with Numbers both require parental participation. Mathematical Reasoning..... worksheets could be used independently.