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Our 6 yo was reluctant at first but once he got started he soon got into the game. It is simple yet effective. I don't think it will last that long though, it will soon be too easy. But as I see it the game is great for reinforcement and even if we only play it 5-10 times in total it is worth the money because he is learning/reinforcing basic addition and subtraction while enjoying maths. Kids just learn quickly when they are having fun! Also it is great for kids who are not so keen on writing and four younger kids who might be able to do the maths but don't have the motoric skills or patience to write the numbers properly.
I bought this for my 4 year old as she was doing adding & subtracting to 10 at school. We used it with some number blocks to help her with the sums & visualise the amounts. She really enjoyed it and it has helped her massively with simple sums.
One of the most popular games I use with my special needs maths classes. Great fun and the pupils barely notice they are doing the sums as so involved with trying to avoid the POPS! The literacy ones are also excellent