I have not research on how to teach the boy division. But i've taken the basic step to teach him the concept at the very least.
Division as i know it, is about grouping. I first wrote a division equation on our doodle board 8 divide by 4. I then stamp 8 shapes on the board and had the boy group them in 4s.
I asked the boy how many circles are there, to which he answers 2! I repeated the equation and showed him the answer is 2!
I had him practise a few more equations just so i know he understood the concept.
Although he can't divide mentally nor know that it's actually a reverse of multiplication, i am satisfied for now that he knows what division is about.