It's something of an article of faith in my family that children are natural scientists. Yet another illustration is from a classroom of 8 year olds, who recently published in a professional scientific journal. Yay!
In their case, it was a study of bees and how they identified food. The full paper is here. A nice journalistic coverage is here.
They did have a professional scientist helping figure out things, and doing the writing, etc.. But the fundamental ideas came from the kids.