Personally, I don’t see anything to be concerned about with common core math. If it was a different subject, I’d be more concerned.
But, that said, we use MUS and the common core is a little confusing to me. But that doesn’t make it bad. Instead of just learning to add and carry 325+ 478….they have to break it out into place values, too (they learn both ways). It’s:
300+20+5
+ 400+70+8
And when they get to multiplying that way, it’s more confusing. But there is nothing “immoral” about it, and I love that my kids understand the math concepts doing MUS. So, we try to do it their way unless it’s really baffling for my kid, then I teach them the traditional way. 🙂
Hope that helps.