From TTS Group:
Flip-It Times Tables is the best way to help children (and adults!) to know and understand their times tables. Flip-It started life just a few years ago as a unique, self-checking physical resource primarily used by teachers and children in schools. Developed by Sally Northen, an educator with over 30 years' experience, there are card sets for most schools subject areas that children can find tricky. Flip-It holds children's attention, encourages thinking, aids memory skills, allows for 'over-learning', and is engaging to all ages.