I am sitting with DD today doing the placement tests for singapore math. She's got some obvious gaps which are to do with being taught a different curriculum thus far. I know the standard advice is to buy the whole set of books if there are consistent gaps in a particular area, but I am wondering about just teaching those areas and moving on to higher level books. It seems crazy to buy a whole curriculum for one or two areas that she just haven't covered yet but will clearly pick up in a snap. For example she's clearly not ever seen number bonds represented the way they are in the test she's just done, but she actually knows all of those number pairs and will understand the second it's explained what was actually required.

My only concern is whether the placement test really do indicate all the areas covered and I can just work independently on covering the one or two areas she clearly hasn't seen before?

I am no expert. We are just starting our homeschool adventure tomorrow with my DD8. I bought the 3A and 3B books used without anything else because I wanted to start her officially in 4A. She worked through the 3A but it was mostly new to her, but when I sat down with her on the 3B, she had learned most of it. So, I decided we would do a 2 weeks of the 3B that she had learned as a quick review just to make sure she hadnt forgotten it and I matched the rest of 3B that she hadn't learned with the 4A topics. I will do the 3B explanations and a problem or two to introduce the topic, but then just go straight to the 4A book. If your daughter is very good at Math, an approach like that should be no problem. I got the books used at our local Homeschool Store. So, buying the extra book to fill in the gaps wasnt too much.

Thanks! She's not super mathy, or rather she's not much for the rote skills and repetition of early math. I ended up deciding to start her on 1b as it seems like she's got a few important sections entirely missing, things that are not just a quick "you didn't get what this question meant because you haven't seen it expressed this way before". I suspect we'll rip through it, but there's no rush. Also the books aren't that much in the end.