An uneven surface isn't a bad thing for children. There is a lot to be learned at a young age of how to move and how to maintain balance and children are being deprived of opportunities to challenge themselves in "perfect" play areas. I attended a lecture recently by a couple that are looking at physical education for children in a new way. The husband works with professional athletes internationally and has to teach them basic skills that kids used to learn innately in the past. Children need the chance to walk on uneven surfaces and even how to balance on an unstable surface, like a wobbly rock; how to run, keeping track of their friends while not tripping over things in their path and how to figure out how to cooperate in achieving common goals.