If I switch to Singapore or MM after Rightstart B

[Snowfall]

I don't really need to do 1B, do I? That would be very upsetting. DD already knows her subtraction facts from 1-10 and can do addition using all the usual mental math tricks. She doesn't know any of the tricks for subtraction, though, and RS doesn't even begin to teach any of them until something like lesson 50 of C. RS also doesn't cover multiplication at all until lesson 25 of C, and I know Singapore introduces it in 1B. What I'm wondering is if Singapore has enough review in 2A to allow us to move right into it after B of Righstart. If not, I might stop RS right where we are for a while to do some subtraction lessons from Math Mammoth, once I get it. Does that sound like the best plan? I might use RS for a while still, but the more I look at how long it takes to get to subtraction in C, the more I consider either dropping it, skipping ahead, or setting it aside for a while to cover subtraction in more depth now.

[Allearia]

We just went from RS B into Singapore 2A. The beginning is completely all review. It does seem to go over subtraction again, though my son didn't seem to need a lot of instruction so it depends if your child seems to understand it or not. So far it moved fairly quickly from single digit through multi digit and on to multi digit with trading. We haven't gotten there yet but 2A introduces mutiplication by 2 and 3 later on so I think we will be fine. You could consider getting the extra practice workbook if you think your child will have trouble to practice the subtraction further. We are doing the IP and CWP books and haven't needed more practice though but my son is pretty mathy.

[Snowfall]

Thanks! I had looked MM1b and was very confident we wouldn't need to do anything from it to be ready for MM2A, but then the Singapore placement test had a few subtraction problems and multiplication/division problems I know DD would be able to do with an abacus or something, but not in her head - at least I don't think. I'm glad to know those things are covered from the beginning again in 2A.