Practice makes Perfect!
I did a lot of maths when I was young and so I got all A in public exam.
Now my son, I have him to do a lot of maths ex.
Suggest 3 methods:
- study Kumon (normally this only suitable for those hardworking and high concentration kids)
- buy exercises to do (think of some motivation to have the kid to do)
- I myself develop some excel files which can automatically generate "+-x/" exercise for my son to do.