No one ever said to me, “Your books will make a wonderful wrapped birthday or holiday gift to open,” and I agree. However, Two Plus Two Is Not Five and Five Times Five Is Not Ten are two books which would be wonderful gifts-the gift of math, the gift of learning math facts so as to be successful and confident in the next levels of math.
Too many children, and even some adults who admit it to me, struggle with math, or are afraid of math. Math does not have to be scary. The entire basis for success in math is understanding what numbers mean, the relationship of numbers to each other, and learning, really learning, the math facts so that answers are automatic.
Learning to memorize all the 81 addition, 81 subtraction, and 81 multiplication facts (excluding zero) may sound overwhelming. If taught systematically, and over a period of time, with strategies to help recall the answers, then, no, it becomes easy! My books include the instructions on how to assess known facts, to record which facts are known, and then where to start in the books. (New learners start at the beginning.)

