Below are some fun educational websites with games to support a variety of math skills for each grade level.
The following websites specifically focus on building math fact fluency.
This last group of websites are for educational programs that are non-profit and will work at your child's level after taking a short diagnostic assessment to get a sense of where they are at mathematically. If your teacher doesn't have an account already, you can create a parent account and you will get emails with info on how your child is doing in their lessons.
- khan academy