Multiplication?
First I just qiuizzed him when we were in the car, but it was random. It kind of worked, but did not stick.
Me running through flash cards with him is what really worked. The main reason for the cards is so that you can do I. Order, the shuffle and make them random, and hold out the ones that they get stuck on. Also, get ones with answers on ypur side. After days of this, I admit to going brain dead and forgetting the answer