Indonesia is my mother's homeland and one of my favorite countries. Since I was young, I had learned a lot about the country and become interested in it. For a long time I had wanted to do something for the country and people there, and I thought volunteering（做志愿者） would be a good and fun way to do so.

    I received the greatest pleasure from being with the children.

    Teaching my first English class in Aceh was exciting, but I was rather nervous. As time went by, I learned how to be a better teacher. Teaching was actually the most enjoyable of my many responsibilities(责任).

    Many children were shy at first. But when they relaxed, they would start talking and telling you a lot of funny things. I believed we were helping them build up their confidence.

    For the children who are more in need. The Education Program（TEP） will collect donations(募捐) to help them.

    As a volunteer, I had to visit the TEP children at home once a month and help them write a thank-you letter to their sponsors. This was a way for the children to communicate with their sponsors. Sometimes the sponsors would write back to the children. Seeing the children's happy faces, I had a great sense of pleasure.

    Homeless people face a lot of challenges, - such as not having enough to eat and no job opportunities. Some of the most basic challenges, - however, -are not having clean water and toiletries (卫生用品)-a big problem for homeless teens. That encouraged a young researcher to invent a multi-purpose product to help these teens.

    "I was born into a life of volunteering," said 13-year-old Leia Gluckman. And that's true. Her mom is a president of an organization providing help for homeless teens. Leia and her brother have volunteered there for years. When she was a young girl, Leia helped serve food where teens were eating. Now she's a teenager herself, and she's managing the toiletry and clothing work there.

    From her work at the center, Leia noticed that teens asked for some toiletries more than others. What they needed most often were toothpaste, body powder (粉)and shampoo(洗发水).Leia wondered whether she could create a product to serve all three purposes.

    It would need to take away dirt and oil from skin and hair. It would need to clean teeth. Also, it would need to kill bacteria (病菌)without being harmful to people. She wanted her ingredients (产品成分)to be natural, to be able to break down easily and to taste and smell pleasant. Moreover, this product had to be low﹣cost and have a long shelf life.

    Leia started by going to stores and looking at the ingredient lists for toiletries. Then she tried eight different ways. She tested each way to see how well it worked.

    Not all of them worked well. But she finally decided on three. Each includes salt and baking powder. Salt helps clean teeth and skin; baking powder helps take in bad smells. She also has some other recipes which include some special materials that give her products different tastes and smells, which would let teens choose a product based on personal preferences.

    It wasn't easy, but Leia came up with some model products. She presented them at the finals of Broadcom MASTERS science competition.

    Leia wants to develop her products further. "Could it possibly be used to drive away mosquitoes (蚊子)?" she wonders.

    "Science offers a way to go about solving problems and helping people," says Leia. And she thinks her products could benefit a great number of people, not just the homeless. Anyone in an area with little or no chance to get clean water could find her products useful, maybe refugees (难民) and soldiers who are sent to places without running water.

How many bicycles do you need in your life? For Chai Lin, the answer is 1,300 and the number is continuing to grow.

Bicycles first came into China in the 19th century. At that time, they were a symbol of having a lot of money. And later they became a common way of transport. When Chai saw some people riding a bicycle, he said,"They were like flying on the streets, and my heart went flying with them."Since then, he dreamed of owning a bike.

However, at that time a bicycle was too expensive for ordinary Chinese. To get enough money sooner, Chai began to sell his pictures in the street. With his own hard work and the help of his family, Chai got his first bike, at the price of 880 yuan, in 1979.

Chai Lin became a businessman years later and he could buy motorbikes and cars. ▲ He began to collect bikes of different brands and ages from around the world in different ways. Up to now, Chai has collected more than 1,300bikes.

With his collection growing, there was no room big enough to keep it. In 2009, with the support of the Gansu provincial government, he spent 200 million yuan building a museum just for exhibiting(展出) his bikes. After 10 years' hard work, the Gansu Sanmu Bicycle Museum in Lanzhou finally opened to the public in January 2019. People can go and enjoy the bikes for free. By 2024, more than two million visitors have been there.

"A large part of my collection is not yet exhibited and has to be kept in other places. I hope to expand (扩大) the museum for my bikes,"he said.