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.
Some have a time limit to complete tasks, much like a game. If the math problems are not completed in time, a buzzer sounds indicating that they are out of time. This raises the competitive level from simply completing tasks to competing for how quickly they can do it, and do it correctly.
They can start with asking simple math questions and going on to harder questions, as the child gets older. Parents should continually ask children mathematical computation questions and give positive feedback when they respond. Children love to receive positive feedback and that encourages continues growth.
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.