Hi,I'm a non-teacher, so I'm only speaking from my experiences as a student, and general reading etc.
I'm not sure how much understanding can be expected of children that young, and maybe they don't need it. The processes of calculation, and numbers, don't need to be understood to be used perfectly, which is why computers are so good while having zero understanding. All the child needs are the tables, in memory, to calculate with, to produce the correct answer 100% of the time. And that success is hugely important to a child because exactitude is something they recognize, and cherish. So to be able to do something perfectly is a wonderful start to their education, and makes Math special. By trying to make kids verbalize things they don't really understand, their failure tarnishes the perfection of math. It's not enough for them to do something perfectly, they also have to give a speech about it. So maybe Math aint so good after all, if being right isn't enough.
They should look on Math as being easy peasy, and being able to do a simple process perfectly, from memory alone, or following a simple rule, should be all they are asked to do. Reward them and move on. There was is apt quote in the Sayings I saw today. "People forget what you say, and what you do, but they never forget how you made them feel." Math can make kids feel bad, which is why so many bright kids turn away from it: they crave success, and Math thwarts them. Let them crunch numbers, rather than the other way round.