A parent must know what level of math and any other subject, for that matter, that their child is performing at every school year. When children enter kindergarten and the school recommends that children know their ABC's and know how to count to twenty or whatever number, it is the parent's responsibility to make sure the child is prepared prior to enrolling in school.
Get in the Kitchen! I was very hesitant for a while with my son when it came to the kitchen. I worried about the GIANT mess that would be left when he was done "helping". You don't even have to take on the entire project with them! You can start small and let your child help with measuring certain ingredients. You can modify the difficulty of the 'lesson' by talking about the different kinds of measuring cups and seeing what other measurements can also add up to equal one cup, etc.
The same general idea worked when it came to my son's Lego's! It was a great way to work on patterns and following directions! I would draw a pattern on paper for him to copy and recreate with his Legos. It not only helped with his color recognition, but his problem solving skills, fine motor skills and he didn't even know he was doing math!!
Another recommendation for parents is to not allow children to utilize calculators at an early age. Children need to first develop their brains to be able to do mathematical computations on their own. Constantly using calculators at a young age can stunt the mathematical growth of children. If children develop math skills by mentally thinking of the answer to simple problems, they will be better prepared for everyday life, such as grocery shopping, balancing a checkbook, to name a few.