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.
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.
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.
Elementary math is the building block on more complex topics that students must learn for the future. From simple addition and subtraction to telling time, it is a fundamental knowledge base used throughout life. Computers are also a basic fundamental building block for the future. Math programs integrate both.