It is good to get in touch with your inner child from time to time，and obviously some people are willing to pay big money for the chance to do so in a proper environment．A Brooklyn-based adult preschool is charging customers between $333 and $999 for the chance to act like a kid again．

At Preschool Mastermind in New York adults get to participate in show—and—tell，arts—and—crafts such as finger paint，games like musical chairs and even take naps．The month-long course also has class picture day where the adults are expected to have a field trip and a parent day.30-year-old Michelle Joni Lapidos，the brain behind the adult preschool，studied childhood education and has always wanted to be a preschool teacher．She's always on the lookout for new ways to get people in touch with the freedom of childhood．A friend encouraged her to start the mastermind course instead．

    According to Candice，her blogger friend，Preschool Mastermind gives adults a chance to relearn and master the things that they failed to understand as children．“I realized all the significances of what we learn in preschool，”said founder Michelle Joni，“People come here and get in touch with their inner child．It's magical．We are bringing ourselves back to another place，another time with ourselves when we are more believing in ourselves，more confident and ready to take on the world.”

    “One person's here because they want to learn not to be so serious．”Michelle said．“Another's here to learn to be more confident.” She explained that most of the classes were planned．However，Joni added that while the planned activities were fun，it was often the spontaneous(自发的)moments that attracted students．“It's the things you don't plan for，the sharing between friends and learning from each other.''

    Recently a new study has been carried out. It shows students who write notes by hand during lectures perform better on exams than those who use laptops.

    Students are increasingly using laptops for note-taking because of speed and legibility (清晰度). But the research has found laptop users are less able to remember and apply the concepts they have been taught.

    Researchers performed experiments that aimed to find out whether using a laptop increased the tendency to make notes “mindlessly” by taking down word for word what the professors said.

    In the first experiment, students were given either a laptop or pen and paper. They listened to the same lectures and were told to use their usual note-taking skills. Thirty minutes after the talk, they were examined on their ability to remember facts and on how well they understood concepts.

    The researchers found that laptop users took twice as many notes as those who wrote by hand. However, the typists performed worse at remembering and applying the concepts. Both groups scored similarly when it came to memorizing facts.

    The researchers' report said, “While more notes are beneficial, if the notes are taken mindlessly, as is more likely the case on a laptop, the benefit disappears.”

    In another experiment aimed at testing long-term memory, students took notes as before but were tested a week after the lecture. This time, the students who wrote notes by hand performed significantly better on the exam.

    These two experiments suggest that handwritten notes are not only better for immediate learning and understanding, but that they also lead to superior revision in the future.

    About 5,000 children die each day due to preventable diseases such as cholera and dysentery (痢疾) , which spread when people use unclean water for drinking or cooking. A lack of water for personal health leads to the spread of totally preventable diseases like trachoma, which has blinded some six million people.

    Water troubles also trap many low-income families in a cycle of poverty and poor education and the poorest suffer most from lack of access to water. People who spend much of their time on ill health, caring for sick children, or collecting water at distances averaging 3.75 miles a day don't have educational and economic opportunities to better their lives.

    Agriculture is called the lion's share of freshwater worldwide, using some 70 percent, and industrial uses consume another 22 percent. Water areas have no political borders and nations don't always work together to share common resources, so water can be a frequent source of international conflict as well.

    Day-by-day demand keeps growing, further needing water sources, from great rivers to groundwater. “We're going deeper into debt on our groundwater use,” Postel said, “and that has very significant impacts on global water security. The rate of groundwater consumption has doubled since 1960.”

    Some of Earth's groundwater is fossil water created when Earth's climate was far different. Today such water is as limited as petrol. “But we're pumping much of them out faster than ever,” Postel explained. “Humanity's growing thirst also causes a major problem about water and our ecosystems. And that also creates a cost to us, to our sons and to our grandsons, not just to nature.”

    Based on the State Information Center (SIC)'s definition for a sharing economy, payment for knowledge can be regarded as a process of turning knowledge into commercial products or services. To be specific, people can share their knowledge with others via Internet platforms, meanwhile bringing themselves extra income. These platforms, at the same time, earn their profits on that.

    The year 2016 marked the beginning of knowledge payment in China. An investigation jointly conducted by Guokr and Netease's online platforms shows that 70% of users have paid for online learning; while in 2015, the number was only 26%.

In May, 2016, Zhihu, a Chinese question-and-answer website, launched Zhihu Live (payment sharing). Within three days, these new platforms attracted over one million users. In June, Luo Zhenyu, founder of LUOgic Show, launched Li Xiang's Commercial References on iget(得到网)，and within two days over four million users subscribed; in August, Z/"7m's approval & tip function, Snowball O&A, Lenovo's Zhiliao Q&A came online; in September, Huxiu (虎嗅网)began to provide in-depth reports to VIP payment members. Other paid knowledge platforms such as Ximalaya FM, Douban，have also been developing their knowledge payment services.

    People with a wealth of knowledge and experience in specific areas are the most likely to benefit from payment for knowledge. Senior managers in large multinational companies like Google, financial elites with top university backgrounds and well-known psychologists, can all profit from these online platforms. But the opportunities also favor the ordinary: a body-builder, a girl who traveled around the world, or a student that passed a postgraduate entry exam can all set up a live classroom. One hundred minutes of audio sharing cost ¥ 19.9 or $2.9, and thousands of users might pay and join the course, bringing those with specific knowledge remarkable income.

    In the 2017 China's Sharing Economy Development Report provided by the SIC，the turnover in China's knowledge market measures about Y61 billion, or $9 billion，which is a 205% growth compared to last year; the number of payment for knowledge users reached 300 million, accounting for half of all Chinese Internet Users.

    The investigation shows that, males are the majority of the users, accounting for nearly 60%: 25-35 year olds account for 59.3%, which mirrors the majority of Internet users, 63% of the paying users are college graduates, and 53.9% of the paying users have an income of Y3-8k,or $ 441-1176, and most are employees and junior management.

    It seems that electronic devices just keep getting smaller. Scientists in the United States have announced the creation of the first transistor with only two dimensions(二维).

    A transistor is a small electronic device that transfers or carries electronic current. Scientists hope these new 2D transistors will be used for building high-resolution(高分辨率)displays that need very little energy.

    Two groups of scientists created these 2D transistors. They report that the transistors are only a few atoms thick.

    Usually transistors are made with the element silicon(硅). Computer processors, memory chips, TV screens and other electronic devices contain billions of silicon-based transistors. But these very small electrical parts have certain limitations.

    Dimitris Ioannou is an electrical engineering professor at George Mason University. He says the traditional transistor has been improved as much as it can be. He adds that researchers have been looking for new materials with special features and they want transistors to be seen through and soft.

    "If the layers are very thin, the transistor can become flexible, so it doesn't have to be rigid(坚硬的), like it would be in a silicon chip. So people can think of applications like wearable electronics, television screens and other things," said Ioannou.

    These new transistors can also carry higher current. They also can move the current much faster than traditional transistors. This is important for high-definition screens.

    Dimitris Ioannou says the scientific success could prove very useful in the future. "Now, how good and how useful it will be, it's still in the stage of research, but it certainly is an advance," said Ioannou.