What is the hottest topic at your school recently? In Taiyuan No.55 Middle School, it's money. The school held an activity called "making money" last weekend. About 200 Junior 1 and Junior 2 students were divided into 30 teams. They went out to make money by selling things. What did they choose to sell? Some sold newspapers; some chose bottled water; some sold environmentally friendly shopping bags and bamboo baskets. Hu Qing's team decided to sell some useful books in front of the Children Activity Center. They thought parents would like to buy the books for their children. But unfortunately, they met urban management officers  . The officers asked them to leave. "We played hide-and-seek   with the officers for the whole morning" said Hu. "Finally we had to give up." Wang Bing and her team sold ice cream in a square. They didn't meet any officers. But few people were interested in what they were selling. The team then put up a board saying "For Country Kids". It worked. More people came to their stall  . A foreigner even gave them 100 yuan. "He didn't want any change. He said he wanted to help the children," said Wang. "We were touched." Later that day they gave the 100 yuan and more to the "Project Hope" office. Meng Zhaoxiang and his team were luckier. They sold all their cakes in four hours, spending 39.5 yuan and getting back 80 yuan. They made 40.5 yuan. "It was not easy to make the money," said Meng. "Some people just looked. Others just tasted but didn't buy. Now I know how hard it is for our parents to make the money we need to lead happy lives." According to the passage the students learn   _  .
it's impossible for them to make money it's not easy for their parents to make money it's very important for them to make a living it's necessary for school to hold more activities in the future