We often confuse problem solving for knowing how to solve a problem. This is so ridiculously simple. There are more problems for which you don't know the answer but can still figure out, with a bit of imagination and creativity, than problems that you could actually know the answer to already. I have been leading kids in developing new ways of thinking at Kids Science Labs for a decade, and the overwhelming evidence (not to mention the academic research) is that kids under 6, before they finish Kindergarten, have far greater problem solving ability than adults. The science is pretty simple. Adults lack (or at least choose not to exercise) their imagination, whereas imagination is one of the primary ways in which kids in early childhood solve a problem. Try it yourself. Ask a kid how to get to the moon, or where dragons live, and they will give you an answer. A real plausible answer, except that when you hear it as an adult, you can reject that solution because you think its simply not possible. You lack imagination.