Originally Posted by ljoy
1+2=3, and ALSO 3-1=2 and 3-2=1. Sometimes 2+1=3 is also explicitly included. Multiplication/division families also exist, of course.

This is intended to strengthen the connection between addition and subtraction for those who don't just see it. I apparently comprehend backwards, since it is beyond obvious to me and always has been, and just look confused at them when they offer this to my daughters as an example of their new, deep approach to mathematical concepts.


I agree! I don't see how it is helpful, but probably because I just get the relationships, I guess for those who don't understand it intuitvely need it spelled out, and maybe it helps them learn the basics easier.