My kindergarten son finished lvl A mid year (we had started in the spring) and we immediately moved on to lvl B. There was a lot of overlapping in the first few lessons that my son wanted to skip so we quickly breezed through the beginning of book B but now that we are in the middle of it we are taking our time again and really enjoying math. It is my son's favorite subject and the one he asks for even on days off. I love how easy RSM is to use. I can't imagine using any other program.