I have used Cuisenaire rods since 1972 when a high school student had no conception of math until he used them in my learning disabilities class. I did the beginning exercises (separating them by color and size) and then--because they are beautiful--he mostly wanted to make gorgeous two-dimensional designs. He was totally engaged for half an hour to an hour at a time. I believe totally engaged students are usually learning something important. That summer his math teacher asked what I had done. Apparently he had started to completely understand math and math concepts which were previously opaque; He had learned something essential. Since then I have used them successfully for addition, subtraction, and algebra--they are perfect to teach the 'new' math of an equation with a hole (unknown) in the middle. A must for math concepts.