Sonya explained that what she (and I) would think of as mental math was not what Charlotte did. Such as 3+5=8+4=12-7=5, etc.
Charlotte did, for example…
There were a lady, a dog, and a butcher’s boy walking down the street. How many creatures were there? How many legs?
She gave harder examples as well but they would be harder to type out!
They were more like multi-step story problems. I’m sure any book of good word problems would be good to have handy. There may be examples in the math book SCM sells but it’s always checked out!! (I’m going to seize it when it comes back in.)