I suppose if you were trying to teach them about 3 of anything, you could try doing it in terms of "one, two and then another one"? That might work.
But then, from dear Brother Lost Sheep's original post I see this:
The word for "one" can also mean "a few", while "two" can also be used to refer to "not many".
So they might think you were talking about a few, not many and then another few. Which has to be a whole lot more than 3, right?
Imagine the problem if you had even a modest number of children, like 6! You'd never be able to keep track of them, and if up to 4 of them had been killed and/or eaten by she-bears you wouldn't even notice.