When I made the decision to use HOD, I also got Singapore math for my oldest two children, and for a while they were doing that AND Rod & Staff math, until I could make up my mind which one to do! My children begged for Singapore to be the winner. They were thrilled when I told them that Daddy and I had decided that we would drop R&S math and just do Singapore. This was back in July sometime.
My 6-year-old is great at math. He'll be done with Singapore 1A next week. Today, out of the blue, he says, "I want to do Rod & Staff math."

What a turkey! I told him we are doing Singapore now, so we did a lesson of that. Then, to satisfy his sudden craving for R&S math, I copied one of the blackline masters I have of addition and subtraction problems. There's got to be at least 100 problems on this page. He looked at it and asked, "Do I have to do ALL of these?"

I told him to do two lines of it. He finished quickly and then I didn't hear anymore about R&S math after that...
