When I was in middle school, we used the Saxon method of learning math. Every lesson set contained new concepts AND forced students to answer questions to old

When I was in middle school, we used the Saxon method of learning math. Every lesson set contained new concepts AND forced students to answer questions to old concepts. By the end of the year, we were fluent in all the concepts regardless of the last time they were taught in class, because we were constantly forced to solve equations from all parts of the book. We all loved that approach because it kept us in practice.