Anything less could cause children to suffer a tremendous loss. The teacher that parents should be trusting to teach their child math is a person that will challenge their child regardless of their age. In addition to the challenges, the teacher should encourage children to try hard. Children need to know that their teacher cares about them and is not just trying to give them a lot of hard work.
In addition to mental math activities, children should be given grade level mathematics workbooks to strengthen their math skills. Parents should have these books and other subject content books at home for additional practice and homework. These can be purchased from bookstores, teacher supply stores and multiple-purpose department stores where school or office supplies are sold.
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.
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.