What works:
1. having a lecture on a chalkboard
2. taking notes by hand. Yes, by hand. Something about the act of writing it by hand fixes it in my brain
3. using pencil and paper to do the problems.
4. and what really works is giving an in-person lecture on how to do it
What doesn't work:
1. everything else
I've watched many instructional videos. Poof, none of it sticks. I've audited classes. Poof, none of it sticks, because I didn't do the homework.
I've never known anyone who learned arithmetic from a calculator.
It's like wanting to be strong. You have to do the work to get strong. There is no substitute.