Can you see a brain grow?

So I think my boys' brains are going through a growth spurt. Here are some of the questions I've had to field while riding in the car lately:

• Why is gum white?
• What is the difference between a kid and a baby? Is a baby a kid? Is a kid a baby? When does a baby turn into a kid? Am I a baby or a kid or a baby and a kid? When will I be an adult?
• Is a mosquito the smallest insect? (no, I informed them--you know what's next) So what is the smallest insect? (guesses anyone? remember I'm in the car--no internet access)
• Do dogs like water?
• Why do terradactyls (yes I had to look up the spelling) have wings?
• What are campers and sprinklers for? (no idea how those two got connected)
• What do banana splits taste like?
• What are the buttons for (at the drive thru at the bank)?
• What's a check?
• And my personal favorite from John: "What does "since" mean?" (As in "we haven't seen Grandpa & Grandma since vacation") "I know that "cents" means change for money but what does "since" mean?" (That one took me awhile.)

And keep in mind the last 7 question were just on the way to the bank the other morning. And my bank is less than 1 mile away in a very small town. No wonder my head hurt by lunch. I feel like I've gone back to school. I'm surprised I can't physically see their brains growing.