I used Math Mammoth in first grade for my daughter and now we’re all back to it after stumbling over Singapore Primary Math. I did a bit orally with my dd back then, because she didn’t like writing too much and sometimes it saved a bit of time. I noticed in her book this year, there are several “greyed” blocked areas where Maria Miller (author) says you don’t have to write, but should do it orally. I do still have to read quite a bit to my dd (3rd grade) as she confuses instructions at times. HTH. I am afraid I do not know much about CM’s views on Math.
All the best,
Lindy