Nationally, there is a movement toward standards-based teaching in mathematics education.
The main idea of standards-based teaching, that every school and classroom works from a common defined set of standards, and that therefore, a curriculum will be designed and then implemented based on those standards, certainly sounds better than the alternative of no standards. Sadly, too many of our schools don't even know what standards are, and they define what they teach by how far through the textbook they happen to got.
Standards are enforced by assessments that claim to test exactly the standards. The whole thing is then an engineering process: write standards, write assessments to match standard, tell teachers to teach exactly that, repeat until proficient.
With the standards based zeitgeist also come the ideas of data driven instruction--check the outputs! test what they know! adapt accordingly. This gives you time to see if your student will pass the assessment before the student takes it.
But most schools still don't know how to teach to these standards, so they look to textbook publishers who claim to help. Because this push was national, Common Core was adopted nationally, giving the textbook publishers one non-moving target to hit.
The good news: Spiral Math is losing its grip. It would seem that publishers couldn't figure out how to map standards onto their spiral's scope and sequence, and opted instead to order their books to match Common Core. And schools want new textbooks. Because how can you do interim data driven instruction assessments in november and checkbox which standards your kids have passed if they haven't seen the material completely until May?
The bad news: at least some of the new textbooks teach Common core standards in order. exact lexicographic order in some cases. First the operations strand, then number and operation base ten, then number and op fractions, then the decimals, geometry strand, etc.
Why is this bad? Because while Common Core is far more coherent than most, if not all state standards to date, the authors did not seem to understand that this line-by-line method would be how schools and publishers implement the teaching of the standards.
But, at least now it will be a lot easier to afterschool your child with Singapore's Primary Math because at least the sequence is stable.
More on cargo cult education in standards based mathematics teaching in a couple days.