I'm constantly flummoxed by the off-the-wall questions I get from my kids. Like the time my older daughter, then 5, asked me why her stuffed-pig lovey doesn't have a penis. He's a boy, isn't he? My profound lack of adequate answers was never more clearly on display. I'm faced with stumpers like this practically every day, usually when I'm busy cooking dinner or driving down the highway. What do groundhogs eat? Why do mommies have milk in them and daddies don't? What number comes after twenty-'leven? Why isn't a tooth too heavy for the tooth fairy to carry? Can she fly with it? Will her wings break? What if she crashes? (See more funny questions kids ask.)

Face it, with kids, pretty much no topic goes unexplored. And while I can't help anyone with twenty-'leven (or, for that matter, the dining habits of groundhogs), I have found some answers to the questions you've probably asked.

Why do kids ask so many questions?

They're trying to make sense of a pretty baffling world, says Carol Faulkner, Ph.D., a child psychologist at Bradley Hospital in Providence. "Being a little kid is like being an adult in a foreign country," she says. "They have new experiences and sensations every day. Sometimes it's fun, but sometimes it's confusing."

The constant queries demonstrate that your child is on track developmentally. What's more, the type of questions he's likely to ask correlates to his age:

2 years old: He's going through a language boom and will ask mostly labeling questions: "What's that?" Your answers increase his vocabulary.

3 years old: As his brain develops, he'll work himself up to the "whys": "Why is it dark at night?" Now your responses help him understand what he sees.

4 years old and up: He's realizing there's a world outside his own sensory experience (there once were dinosaurs, even though they don't exist now, for instance), so he'll build up to more complex questions, often based on how things work together: "How does a car run?"

Lisa Tucker McElroy is the author of nine books for kids, including Love, Lizzie: Letters to a Military Mom.