Big Scary Grates

So, I'm currently in DC. I love DC, all the hustle and bustle without the claustrophobic feeling of NYC and a better metro system. A colleague and I are walking down the street and this little boy, about 4 years old is walking by himself. (he had an action figure in his hand) His dad is about 10 feet ahead of him. What separates them? One of those metal grates in the sidewalk you find in big cities. The kid is just staring down into the grate like he can see to the bottom. Not afraid, just completely absorbed by this big metal thing in the sidewalk. The dad did good, just let him look and figure it out. It was adorable. Ah, to be curious instead of irritated that it ate the heel of your shoe.