cool help with addition and subtraction with "big" numbers for a 7 year old

[tiggersreturn]

My 7 year old ds has a lot of difficulty dealing with any 2 digit or 3 digit number over 20. I have tried showing him the method I use (old fashioned you just have to know how to do it to 10, borrow 1 etc) but he refuses to write it down and says he wants to do it in his head like those in the top group. Any ideas of a program/youtube video that can get him to do the basics whether in head or on paper and motivate him?

Start with numberlines.
Do it visually.
When he is secure doing it with number-lines, then he can move on to doing it in his head using the same chunks.

Don't go on to column methods until he is secure with numberlines, they help give a sense of size, place etc rather than just doing a method without understanding.

Also, aim to use the same methods as the school, it can be confusing otherwise.
Maybe ask them about number-lines.

we did numberlines and I thought he had got it but I guess we just have to revise them again.

these things tend to need revisiting before they are secure (at least with my children)

FWIW, I thought DD had done all this in yr1 too. Maybe it slipped over the summer (and number lines baffle me), but I asked yr2 teacher to revise it with her as we've just switched schools.

Ask his teacher to clarify what method he's using, and only use that. DD, also 7, did structured number lines, then unstructured numberlines, and she's just shown me column addition without carrying (she'll be doing carrying next week).

No point in using methods ahead of what he's doing in school. We actively avoid showing them the way we used to do it in case it confuses. I think the new ways are better. It's not just a mechanical process, it teaches them to understand what they are doing much more than the way I learned IMO.