I would not be so quick to dismiss this as a common core issue. It sounds like a teaching issue. There are two ways for teaching young kids to set up subtraction problem. Kids typically get the taking away something problems very easily. The comparison problem is harder for most kids. It sounds like your daughter was not familiar with the comparison set up and the teacher didn't get through to her.

As for number bounds and decomposition, that is exactly how Singapore Math teaches it, SM is hardly common core.

Last edited by Thomas Percy; 04/14/16 06:51 PM.