On Monday, I stopped my car in front of my daughter Juliet's middle school. She jumped in the front seat, feeling down. She asked me to help her study for her science test.

    "Dad I need to memorize a unit about the Reproductive Cycle of Plants. And I can hardly make it."

    "You know memorizing seems like the best way to study, but in fact you can do better in tests if you work on trying to understand the material."

    Juliet was open to my advice. It was Monday afternoon and we had two nights to study before the test on Wednesday. I suggested a plan. "Tomorrow night, you are going to teach the material to me. Tonight, read the unit. Prepare to teach."

    Asking her to teach me was an unusual idea but I was determined to do it. Studies show teaching somebody else is a very useful way to lean, Even if you don't do the teaching, the act of preparing to teach leads to more learning than just trying your best to memorize the material.

    On Tuesday afternoon, Juliet sat down with her Science book facing me said, "Okay Dad, let's study." I wanted her to teach me. But false starts happened. I couldn't be too hard on her. So instead we starred with me asking her some simple questions. She knew some but not other. When she didn't know the answers. I encouraged her to check the book.

    She started checking things that didn't make sense. And she was actively seeking to test her understanding. I was happy to see it. She wasn't memorizing, she was trying to make sense of things, which was exactly what I had hoped she would do.

    Elena jogged with her dad in some empty lots(空地)at the edge of town. These out-of-the-way lots were good places to jog. But the lots were full of rocks and rubbish.

    One day, Elena saw a sign on the lots. It said, "New City Park. " Elena was excited.

Maybe the park would have a jogging trail(小路)！Elena told her parents about the sign.

    "I read about the park in the newspaper, "said Elena's father. " The city wants volunteers to help clean the area. Then the city will build a soccer field and a playground. "

    "Will they build a jogging trail? "Elena asked.

    " No, the paper didn't mention a jogging trail. "

    "Well, perhaps if I help clean up the lots, they'll put in a jogging trail, "said Elena.

    On Saturday Elena went to the lots. Many adults were working there. Some were picking rubbish. Some were moving rocks. "I want to volunteer, "Elena told a man, "What can I do? "

    "This is not a job for children, "said the man. " You'd better go home. "

    Elena looked around. She could carry rubbish. She could move rocks. A lady was pulling a bag of rubbish. Elena saw a box of rubbish bags. She took an empty bag. " I'll take this bag to the Dumpster, "said Elena, "Here's a new bag. "

    "Thanks, "said the lady. " Keep those new bags coming. "

    Elena dragged rubbish bags. She told everyone she was glad to help build the park. She explained that she hoped the park would have a jogging trail.

    Elena went to the area every week. Soon everyone knew her and she told everyone how wonderful a jogging trail would be.

    Soon the volunteers cleared the lots. The city could start building. The mayor gave a speech. He showed a drawing of the new park. He told them about the soccer field and the baseball diamond. There would be picnic tables. There would be a playground. The park would even have basketball courts. There was no sign of a jogging trail.

    The mayor thanked the volunteers. Then he asked if they had any suggestions. The volunteers said they wanted to build a jogging trail around the park. They told the mayor how helpful Elena had been and how she wanted a jogging trail. The mayor said, "A jogging trail won't be hard to build. Let's do it！"Everyone clapped and cheered. Elena cheered loudest of all.