题目内容：

One evening, I found an electric (电动的) model car on my 6-year-old son’s desk. We hadn’t bought one like that for him. At dinner, I asked my son about it.

“I exchanged my paper model plane from a little girl in the neighborhood.” he said.

We were surprised. The paper model plane really cost nothing. But the electric model car might cost 15 dollars at least. We thought our son might tell a lie. But we said nothing.

The next day, I took my son to the little girl’s home with the electric model car. I was going to make sure whether my son told us a lie, and to return the model car to the girl.

But the little girl’s mother told me that it was true.

“The electric model car belongs to my daughter. It is up to her. I respect her decision.” She said. “Since your son likes the electric model car, it belongs to him.”

Then I took the girl with us to a toy store. I bought an electric model plane to her. And I wanted the girl to understand whether it was worth exchanging an electric model car for a paper plane.

Since then, they have been good friends all their lives.

Education is really an art. It was lucky that we didn’t scold (训斥) our son before we learned about the fact.

1.What did the boy exchange his paper model plane for with the little girl?（不超过5个单词）

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2.What’s the mother’s opinion on her daughter’s exchange?（不超过5个单词）

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3.What does the writer want to tell us?（不超过15个词）

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