Not sure if anyone can help with this but here goes.

Ming I have this exact problem with my daughter, maths is an area she is really struggling with. She is above average with reading/writing but her maths is below average. Like your son you can ask her a maths question, something simple like 10+12 and she will sometimes get it, ask her straight after what 12+10 is and she seems unable to process that it's the same question and will have the same result even when I tell her the numbers are just swapped around she will still sit and struggle to add it up. 

I've tried bringing it up with her teacher but she doesn't see it as a problem, even after I stressed just how much she struggles and how one minute she can get it and the next she has no idea what she's doing. She came home from school once upset because they'd had maths and they'd been using calculators and all the other kids got their questions right except her, she'd only got 3 questions right. I couldn't understand how she'd got the answers wrong when they were using a calculator, so I gave her some questions and a calculator and watched her do them she got the first few right, then she had 9+12 and she typed it in right and it showed up the answer '21' she wrote down 51. So I asked her to just check again and she did and said 51, so I typed in 22 on the calculator and asked what number it was and she said 55. 

She often gets her numbers mixed up putting 6 instead of 9 or writing S instead of 5, I brought this up with the teacher who again didn't think it was a problem but she's in year 3 surely she should not still be making the same mistakes as when she was in reception. She's been learning maths since pre-school so in total 4 years now and she will still check with me whether + means add, - is subtract, when I ask her if she doesn't know she laughs nervously and says yes but she needs to check (I always reassure her that it's okay if she doesn't know but then she becomes defensive and embarassed).

Another problem she has is that she's a very visual thinker something her year 2 teacher picked up on and she did in the last few weeks try to help my daughter more and asked us in to show us some games we could play etc to help her. She no longer gets that help in school now she is in year 3 but when she has maths homework we use visual methods (her monster high doll obsession) to help her. So if she has simple sums like 13+8 we get 13 dolls and place them in one pile and 8 dolls and place them in another and she can do the sum. Same with if the number gets bigger 52+33, we have 2 piles still but we use the girls as the units and the boys as the tens. So instantly she can see that she has 8 boy dolls out and 5 girl dolls and she almost instantly says 85, wheras if she tried to work it out in her head or on her fingers she will sit for a good few minutes before getting the answer wrong and she becomes increasingly frustrated with it.

I'm pretty sure she has dyscalculia as she often does things like misses numbers out when she counts and if she has to count in 2's it takes her quite a while and she can get muddled up and still doesn't fully know her left from right but her teacher is adamant that she will improve.

I do wonder how far behind the teacher will allow her to fall before allowing her extra support, we had her report last week and it has predictions for end of year achievements based on their current level/understanding. For her year they excpect the kids to be a 2a/3c in the 3 r's, she is expected to be 3c in writing, 2a in reading and 2c in maths and yet nothing is being done about that. Again it's on our shoulders to get her help and I'm having to look for a private maths tutor as well as do what I can to help her now.

Some other things I do to help is buy her little maths books aimed at kids, so she had a tinkerbell one the other week and she loved doing it as again it was very visual and she got most of the questions right. I've downloaded maths apps on my tablet that she plays now and again and any opportunity I can to bring maths up I do. So if she wants to get a comic that costs £2.99, I ask her how much change she will have if I giver her 500 pennies in the form of a £5 note, most of the time she will get muddled but now and again she manages it. We also have exercise breaks in the middle of homework time because she starts to get fidgety and her OT has said she needs alot of physical movement to self-regulate, so we will do maybe 5 sums and then I tell her to run around the house, do star jumps etc for a few minutes and then she is calm enough to concentrate again.

I hope you find something that works for your son Ming, good luck :)

Ming I have this exact problem with my daughter, maths is an area she is really struggling with. She is above average with reading/writing but her maths is below average. Like your son you can ask her a maths question, something simple like 10+12 and she will sometimes get it, ask her straight after what 12+10 is and she seems unable to process that it's the same question and will have the same result even when I tell her the numbers are just swapped around she will still sit and struggle to add it up. 

I've tried bringing it up with her teacher but she doesn't see it as a problem, even after I stressed just how much she struggles and how one minute she can get it and the next she has no idea what she's doing. She came home from school once upset because they'd had maths and they'd been using calculators and all the other kids got their questions right except her, she'd only got 3 questions right. I couldn't understand how she'd got the answers wrong when they were using a calculator, so I gave her some questions and a calculator and watched her do them she got the first few right, then she had 9+12 and she typed it in right and it showed up the answer '21' she wrote down 51. So I asked her to just check again and she did and said 51, so I typed in 22 on the calculator and asked what number it was and she said 55. 

She often gets her numbers mixed up putting 6 instead of 9 or writing S instead of 5, I brought this up with the teacher who again didn't think it was a problem but she's in year 3 surely she should not still be making the same mistakes as when she was in reception. She's been learning maths since pre-school so in total 4 years now and she will still check with me whether + means add, - is subtract, when I ask her if she doesn't know she laughs nervously and says yes but she needs to check (I always reassure her that it's okay if she doesn't know but then she becomes defensive and embarassed).

Another problem she has is that she's a very visual thinker something her year 2 teacher picked up on and she did in the last few weeks try to help my daughter more and asked us in to show us some games we could play etc to help her. She no longer gets that help in school now she is in year 3 but when she has maths homework we use visual methods (her monster high doll obsession) to help her. So if she has simple sums like 13+8 we get 13 dolls and place them in one pile and 8 dolls and place them in another and she can do the sum. Same with if the number gets bigger 52+33, we have 2 piles still but we use the girls as the units and the boys as the tens. So instantly she can see that she has 8 boy dolls out and 5 girl dolls and she almost instantly says 85, wheras if she tried to work it out in her head or on her fingers she will sit for a good few minutes before getting the answer wrong and she becomes increasingly frustrated with it.

I'm pretty sure she has dyscalculia as she often does things like misses numbers out when she counts and if she has to count in 2's it takes her quite a while and she can get muddled up and still doesn't fully know her left from right but her teacher is adamant that she will improve.

I do wonder how far behind the teacher will allow her to fall before allowing her extra support, we had her report last week and it has predictions for end of year achievements based on their current level/understanding. For her year they excpect the kids to be a 2a/3c in the 3 r's, she is expected to be 3c in writing, 2a in reading and 2c in maths and yet nothing is being done about that. Again it's on our shoulders to get her help and I'm having to look for a private maths tutor as well as do what I can to help her now.

Some other things I do to help is buy her little maths books aimed at kids, so she had a tinkerbell one the other week and she loved doing it as again it was very visual and she got most of the questions right. I've downloaded maths apps on my tablet that she plays now and again and any opportunity I can to bring maths up I do. So if she wants to get a comic that costs £2.99, I ask her how much change she will have if I giver her 500 pennies in the form of a £5 note, most of the time she will get muddled but now and again she manages it. We also have exercise breaks in the middle of homework time because she starts to get fidgety and her OT has said she needs alot of physical movement to self-regulate, so we will do maybe 5 sums and then I tell her to run around the house, do star jumps etc for a few minutes and then she is calm enough to concentrate again.

I hope you find something that works for your son Ming, good luck :)