Becky and Steve walked to school on a winter morning. Becky wore a hat and gloves but no scarf. Steve wore a hat and two scarves, but he didn't have any gloves. They both felt very cold. 

Then Becky had an idea! "What if I trade you one glove for one of your scarves?", Becky said. "Then both of our necks would be warm, and we'd each have one warm hand. We could put the other hand in our pockets."

"Good idea!" said Steve. 

After they shared the scarf and glove, they began to feel warmer. 

A few minutes later Mrs. Brown appeared. "Did I just see you barter?" she asked. 

Becky and Steve looked puzzled(迷惑的). "What's barter?" Becky asked. 

"Barter means trade things without using money", Mrs. Brown explained. "You two traded a scarf and a glove so you could be warm. Did you know that traders bartered for thousands of years?"

"Really? How did it work?" Steve asked. 

Mrs. Brown said, "Well, traders who had too much of one thing, such as salt or cloth or pigs, would exchange them with other traders for other things that they needed. Trading grew and developed, but it had problems."

"Like what?" Becky asked. 

"Suppose you raised chickens. You could trade the chickens and eggs for what you needed. But if the chickens got away..."

"I wouldn't have anything to trade!"

 "Exactly!" said Mrs. Brown. 

"Now you see why people began to use money to trade." Mrs. Brown added. 

"Is it true that silver and gold coins were used before paper money?" Steve asked. 

"Yes, but they were too heavy to carry." Mrs. Brown said. "People then began to write promises on paper instead of trading coins. That was how paper money got its start."

"Wow!" said Becky, "but I guess people still trade sometimes, the way Steve and I did today!"

Parents often believe that they have good relationship with their teenagers. But last summer Joanna and Henry noticed a change in their older son. Suddenly he seemed to talk far more to his friends than to his parents. "The door to his room is always shut," Joanna noted. 

Tina and Mark noticed similar changes in their 14-year-old daughter. "She used to cuddle up against me on the sofa and talk," said Mark. "Now we joke that she does this only when she wants something. Sometimes she wants to be treated like a little girl and sometimes like a young lady. The problem is understanding which time is which." 

Before the age of 11, children like to tell their parents what's on their mind. "In fact parents are the first on the list," said Michael Riera, author of Uncommon Sense for Parents with Teenagers. "This completely changes during the teen years," Riera explained. "They talk to their friends first, then maybe their teachers, and their parents last." 

Parents who know what's going on in their teenagers' lives are in the best position to help them. To break down the wall of silence, parents should create chances to understand what their children want to say, and try to find ways to talk and write to them. And they must give their children a mental break, for children, they also need freedom, though they are young. Another thing parents should remember is that to be a friend, not a manager, with your children is a better way to know them. 

A student stuck a note on his classmate's back while they were at recess (课间休息) one day. The note said "I'm Stupid". He asked the rest of his classmates not to tell the boy. The other students started laughing at the boy, but wouldn't say why.

Soon, it was time for their afternoon math class. Their teacher wrote a difficult problem on the blackboard. No one was able to solve it except the boy with the note on his back.

Ignoring (忽略) the laughter, he walked toward the blackboard and solved the problem. The teacher asked the class to clap for him and took the note off his back. She told him, "It seems that you didn't know about the note your classmate put on your back, but you didn't seem to care anyway."

Then the teacher looked at the rest of the class and said, "Before I punish you all, let me tell you two things. First, all of you will be labeled (贴标签) at one point or another by other people who don't want you to succeed. All you have to do is ignore these labels. You have to take every chance you have to learn, grow and improve. And it seems that none of you are friends with this boy, since none of you were kind enough to tell him about the note. If that's true, then you'd better hope that you have some good friends yourself. Otherwise (否则), you might be the one with a note stuck on your back someday with no one to tell you."