To follow up on HoneyBadger's point, I think a points system can be very valuable. The one tweak I would make would be to modify the recommendation for "30 minutes looking at the test". I suspect for a gifted child with issues of focus or careful attention, that could be counterproductive. I might instead take time to make sure the child knows how to reverse-check each type of problem that will be on the test, so that they can go from the answer they wrote down back to arrive at the original question, and practice that with them. Then offer whatever incentives seem to work for reverse-checking each answer on a practice test, so they spot the careless mistakes. For some kids, reverse-checking the problem is not a boring repetition of the calculation they already did once, but an "extra twist" on the problem that has some fun to it, and has the added advantage of letting them catch errors before they're graded.
My DS6 has a lot of resistance to doing things twice, including explaining something he knows the teacher or coach already knows the answer to. He sees it as arbitrary and repetitive (which is of course true), and has trouble accepting that this is the only way that other people can verify his understanding. An approach that doesn't involve him having to repeat himself is almost always the best option if we want him to cooperate at this stage.
