I'm only a parent - so no expert - but our experience with doing poorly on quizzes was that we used DD1's not liking that feeling to spur her on to do better.
Now in our case we had hoped that a school seeing 18 months of only being in the 11s club (only able to solve 11 simple additions with numbers under 20 - same test each week) might spur them to 'intervene' - but in fact they didn't. So we opted for help outside of school and went for using an on-line maths tutorial.
My personal view is feeling low about your achievement in one area shouldn't affect your overall view of yourself - nobody is good or even great at everything - that's very rare - even in primary school.
If you are struggling in an area - being honest that it's a struggle and putting that work in to do more/ to improve ('perseverance'/ 'ye olde protestant work ethic') can be an incredibly rewarding experience.
DD1 was horribly behind her peers in Y3 and she knew it. We agreed that she needed to do more - found on-line games/ tutorials she liked - put the time in and gradually, and in return for that effort - week by week we all saw an improvement.
DD1's learned all sorts of life lessons through this process that I hope will come in handy next time she finds something difficult or a challenge in future.
Fundamentally - the thing I object to with our school (I don't know if it is all schools) was a general attitude that children are either good at maths or they're not. There was no institutional belief or faith that practicing some of these skills/ having them presented in a number of different ways until the concept/ process made sense - might help students less able to grasp these concepts quickly.
I think it was this attitude that meant the school was not particularly interested in doing more (extra homework/ one to one sessions/ small groups/ etc...) with struggling students.
I stand by my belief that any child can add/ subtract/ multiply/ divide (with the usual caveats of no SN/ disabilities) - it's a matter of absorbing the principles, understanding the methods and getting in that practice so that performing whatever skill is done fairly easily (because it's familiar)/ efficiently.
I think schools make a huge mistake not encouraging more playing of maths related video games. Children adore games anyway - it doesn't seem like 'homework' - and 30 minutes here or there cumulatively really does add up.