The White family-Mr and Mrs White, their sons Eric and Jack, and daughters Anna and Emma sat around their dining table to have their Sunday dinner. 

"What's for dessert (甜点), Mom?" Eric asked his mother.

"Your dad made an apple pie," Mrs White answered.

"Great!" said Eric's sister Emma from her high chair at the end of the table.

"Well, I want fifteen minutes (分钟) of pie," Eric said.

"Fifteen minutes of pie? What does that mean?" asked his brother Jack. He was two years younger than Eric.

"Mrs King is teaching us about time in school," Eric answered. He was in the second grade (年级) and he started to learn how to tell the time on a clock. "She told us that we could divide (分) the clock into four fifteen-minute parts, like the pieces of a pie. Fifteen times (乘) four is sixty and there are sixty minutes in an hour. "

"My good son!" Mrs White smiled.