When buying watercolor paper for kids, you want smooth paper, that's 100lbs or heavier and no smaller than 9x12". Why?
1) Why smooth paper? Because bumpy paper is hard to paint on!
2) Why 100lbs or heavier? Because kids use a lot of water, and if the paper is too thin it will make holes and warp!
3) Why no smaller than 9x12"? Because it's hard to paint small when you are a kid!
Therefore, Fibo recommends any watercolor paper that is between 9x12" and 11x14" and is 100lb in weight or heavier!