Some children are quite smart - possibly smarter than some adults will ever be. Most are not as smart as the average adult, however, and some will never be. None of this is really surprising?
Whether one is dealing with an adult or child, there's no need to make assumptions about intelligence. I mean, some kids can spell and proof read better than adults, or at least type out the word "airport" correctly :)
I think you underestimate the number of kids who are _smart_, because we put them through the same curriculum and then disregard what they say and desire when they are teenagers. It makes it very difficult to see the huge variation.
Whether one is dealing with an adult or child, there's no need to make assumptions about intelligence. I mean, some kids can spell and proof read better than adults, or at least type out the word "airport" correctly :)