[seanflyon]

Just to be clear

"But standardized tests, the SAT, and the ACT are all moving over to Common Core. So our child has to learn this insanity."

which implies that standardized tests test for this particular "counting up" subtraction method. If I understand your statement you are saying that this is not the case.

Right?

[AnimalMuppet]

It's really hard for a standardized test to measure how you subtracted. (Yes, I am aware that it could be done.) But what it really measures is, can you subtract? Do you get the right answers?

Personally, I don't like this approach, because to do one subtraction, you have to do four additions. That's kind of inefficient, in my view. But as sp332 pointed out, the kids should already know how to subtract numbers by this point. If a kid didn't get it before, this curriculum throws a new method at them, hoping that this one will make sense to them. I'm not sure that I have a problem with the approach (though it wouldn't hurt tweak it so as to not confuse the kids who already know how to subtract).

[sp332]

I doubt the count-up method was intended to be a new method. I think the new curriculum had it in the second-grade book, and assumed that former second-graders had seen it there. It's not the textbook makers' fault that the school changed between years.

[sp332]

Common Core standards do not include the counting-up method. So a test that only measures Common-Core compliance would not test for that.