I'm... not seeing the issue. Never heard of Common Core (at least, not by that name), but from what I'm reading here it's basically mental approaches to math recorded as formulaic strategies.
If I see a problem that goes, "1000 - 865 = ?", my brain doesn't sit there and do
1000
- 865
135
No, my brain goes "well it's 200 to get from 800 to 1000, but adding 200 to 865 gets me 1065 so really I need to subtract 65 from 200. 60 from 200 is 140 and I still have another 5 to take away so that's 135". And my brain does that really, really fast, without even really thinking about it.
...if that's really all that Common Core is, then I don't see the problem with it, save that it looks really convoluted when written down.
If I see a problem that goes, "1000 - 865 = ?", my brain doesn't sit there and do
1000
- 865
135
No, my brain goes "well it's 200 to get from 800 to 1000, but adding 200 to 865 gets me 1065 so really I need to subtract 65 from 200. 60 from 200 is 140 and I still have another 5 to take away so that's 135". And my brain does that really, really fast, without even really thinking about it.
...if that's really all that Common Core is, then I don't see the problem with it, save that it looks really convoluted when written down.