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.
For example, all children should learn their multiplication tables by the third grade. They should be able to repeat them, verbally, without using a calculator. Children in elementary school who rely on the calculator for the answers are creating math deficiencies, which could have a negative impact on their math development.
Also, when the child is in the second or third grade and their child can't add simple two digit numbers, it is up to the parent to make sure that their child gets the extra help needed to become successful. Parents cannot wait on the school every time their child has an academic deficiency. Part of being a good parent is making sure that your child functions at the correct grade level throughout their academic career.
Sort it out! The sky is the limit when it comes to finding things to sort! Candy, beans, cotton balls, paper clips... you name it! You can even change around how you want it sorted... one time, sort by color, the next time sort by size or shape! My son had a BLAST when I pulled his Matchbox cars to the school table and we sorted them by color! For younger children, you can make it easier by having 'color cards' and have them match the specific objects to the correct card. Older children can just be told to sort out the items by color, shape, etc.