Go Shopping! : You can cater this to all different ages. For young children, you can do a 'mock shop' and let them pretend to go shopping in a pretend store (your kitchen). Label certain items with easy to read prices and print some pretend money for them to shop with! For older children, you can let them help you in the actual grocery store with a specific shopping list. You can even set specific spending limits and give a specific amount of items and let them determine what they can afford, etc.
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.
This teacher should believe in giving homework every night. Homework reinforces what was taught and learned in class and gives the parent and the teacher a chance to see if the child understands that information.
Elementary teachers and parents play the biggest role in a child's mathematical development, especially from Kindergarten through Fourth Grade. Time spent in school learning math or not learning math can never be replaced. Parents should make sure the elementary math teacher is knowledgeable and is a good teacher.