You see it right away in grade 2 when doing place value for regrouping. Explaining moving a group of 10 leaves them with a blank stare. But they can learn the operations even if the concept is missing, by teaching the procedure. So they have to be walked through inferential work. Measures math reasoning.
Child does oral problem solving.
These kids of course have trouble with problem solving. They don't have a clue. The only way to really help these kids seems to be to use flow charts to organize the known from the unknown. Measures expressive vocabulary. Child is asked for definitions of words.