My daughter has been working through Horizons 2 this year. For the last week or so she has had an enormous amount of double and triple digit addition and subtraction. I say enormous because my first two kids did Math U See and at most had 5 to 8 problems that were the same at a time. I was feeling sorry for her as the big crocodile tears came pouring out over double digit addition with carrying. I decided that we should do some doubles addition to get her memorizing some of her facts. Something Horizons is not good at, but MUS is.
I came in and printed out some worksheets from my favorite free site. This takes about 5 minutes. Mind you, I took almost 20 minutes helping her work through the first 5 problems. I come back with several sheets to work on and she finished all her addition with carrying problems from Horizons, about 20 of them, in less time then it took for me to print out 4 worksheets. I figured she got them wrong or her sly brother and sister helped her. Not only were they all right, but she did them on her own. Tell me, how did that happen?