I had given our daughter, who was 15 at the time, a drivers manual. On the way to town one day, I was coaching her as I drove. I told her to be studying her book so as to be ready when it came time to get her driver's permit.  

"Oh," she said, "I already know everything in the book."  

"You do?" I returned.  

"Yep", she said, very smugly.  

I thought, "OK, we'll just see about that. I'll give her a hard one."  

So I asked her, "How many feet does it take to stop the car if you are driving 60 miles an hour and have to slam on the brakes real hard?"  

"One," she replied.  

"What?" I asked. "One?!"  

She repeated her answer and then because of the confused look on my face, she added. . .  

"Only one, Mom. You always told me never to use my left foot on the brakes, only use my right one."