The term “formal learning” refers to all learning which takes place in the classroom regardless of whether such learning is informed by conservative or progressive ideologies(思想意识). “Informal learning”, on the other hand, is used to refer to learning which takes place outside the classroom.

    These definitions(定义) provide the basic difference between the two models of learning. Formal learning is separated from daily life and may actually promote ways of learning and thinking which often run counter to those obtained form practical daily life. A characteristic feature of formal learning is the centrality of activities which can prepare for the changes of adult life outside the classroom, but it cannot, by its nature, consist of these challenges.

    In doing this, language plays an important role as a major channel for information exchange.  The language of the classroom is more similar to the language used by middle-class families than that used by working-class families. Middle class children thus find it easier to gain the language of the classroom than their working-class classmates.

Informal learning, in contrast, occurs in the setting to which it relates, making learning immediately relevant (相关的). In this context, language does not occupy such an important role: the child's experience of learning is more direct, involving sight, touch, taste, and smell senses that are not used in the classroom. Whereas formal learning is transmitted by teachers selected to perform this role, informal learning is gained as a natural part of child's socialization. Adults or older children who are proficient (熟练的) in skill or activity provide—sometimes unintentionally (无意义地)—target models of behavior in the course of everyday activity.

    Informal learning, therefore, can take place at any time and place. The motivation of learner provides another important difference between the two models of learning. The formal learner is generally motivated by some kind of external goal such as parental approval, social status, and possible financial reward. The informal learner, however, tends to be motivated by successful completion of the task itself and the partial knowledge of adult status.

    Given that learning systems develop as a response to the social and economic contexts in which they are firmly, it is understandable that modern, high urbanized (城市化) societies have concentrated almost specially on the establishment of formal education systems. What these societies have failed to recognize are the ways in which formal learning inhibits the child's multi-sensory acquisition of practical skills. The failure to provide a child with a direct education may in part account for many of the social problems which trouble our societies.

    As the world around them is changing, teenagers continue to need guidance and support from both parents. Studies show that teens who have an active relationship with their fathers are less likely(可能的)to involve themselves in dangerous behaviors and more likely to succeed in school and develop higher self-worth, because their fathers go beyond social expectations to devote attention to them.

    Peer(同龄人)pressure has always been a big part of the teens' experience. Even the best father can't completely protect their kids from the growing influence of their peer group. However, studies show that teenagers whose fathers focus on their lives are more likely to resist (抵抗)the more bad effects of peer pressure, taking drugs, for example.

    Teens may not like to admit it, but they are watching their parents closely and often follow their example. An interesting finding explains just how important parents are, especially Dad. Swiss researchers discovered that if Dad attends church, even though Mom doesn't, 44 percent of the kids are still more likely to keep going to church as adults. But if Mom goes regularly and Dad never shows up, only 2 percent of the kids continue to attend.

    Teenagers face a lot of difficult choices, especially in their later teens. Fathers don't get to make those choices for them, but they can be influenced. For example, teenagers can learn a lot from their parents' concern on what to do when they finish high school. Should they go directly to college and, if so, where? Should they consider going to trade schools, joining the army or looking for a job? A father's guidance brings a long-term perspective that teens often lack to these important decisions.

    Many facts suggest that children are overweight (超重的) and the situation is getting worse, according to the doctors. I feel there are a number of reasons for this.

    Some people blame the fact that we are surrounded by shops selling unhealthy, fatty foods, such as fried chicken and ice cream, at low prices. This has turned out a whole generation of grown-ups who seldom cook a meal for themselves. If there were fewer of these restaurants, then probably children would buy less take-away food.

    There is another argument that blames parents for allowing their children to become overweight. I agree with this, because good eating habits begin early in life, long before children start to visit fast food shops. If children are given fried chicken and chocolate rather than healthy food, or are always allowed to choose what they eat, they will go for sweet and salty foods every time, and this will carry on throughout their lives.

    There is a third reason for this situation. Children these days take very little exercise. They do not walk to school. When they get home, they sit in front of the television or their computers and play computer games. Not only is this an unhealthy pastime (消遣), it also gives them time to eat more unhealthy food. What they need is to go outside and play active games or sports.

    The above are the main reasons for this problem, and therefore we have to encourage young people to be more active, as well as steering them away from fast food shops and bad eating habits.

    Every day, Americans throw away 500 million plastic straws, enough to circle the Earth twice. They are almost never recycled, and simply contribute to the great problem of plastic pollution; eight million tons of plastic is dumped into the oceans every year.

    Plastic straws are now the target of a growing movement to reduce their use. Possibly the first of such campaigns, Be Straw Free was started in 2011 by Milo Cress, who was only nine years old at the lime.

"I noticed that whenever I ordered a drink at a restaurant, it would usually come with a straw in it, and I don' I usually need a straw," he said. "This seemed like a huge waste. Straws are made of oil, a precious and finite resource. Is making single - use plastic straws, which will be used for a matter of minutes before being tossed away, really what we want to do with this resource?"

    Cress started asking restaurants in Burlington, Vermont, where he lived at the time, to stop providing straws automatically to customer and make them optional instead. Many agreed and his request made ripples (涟漪) nationwide. The restaurants that make the switch report a reduction in the number of straws they use between 50 and 80%.

    The anti - straw sentiment has crossed borders into the UK, where straws have been included in a government plan to ban ail plastic waste by 2042.

Last year large pub chain Wetherspoons announced that it would replace plastic straws with paper alternatives across 900 outlets. After the announcement, many smaller chains and pubs across the country followed suit. According to Wetherspoons CEO John Hutson, the move will save 70 million plastic straws a year and the reaction from patrons has been "very positive".

Offering alternatives or making plastic straws optional, rather than banning them completely, is a common trait among these campaigns. "There are many other viable alternatives to single - use plastic drinking straws that are less harmful to the environment, wildlife and humans," said Jackie Nunez, founder of The Last Plastic Straw.

    One of the most outspoken supporters that I know of women and girls is actually a man. As co­founder of the ONE Campaign, my friend Bono spends a lot of time speaking out against global poverty (贫困). Together, we're working to get out a simple, powerful message: poverty is sexist.

    Women and girls are more likely to be in poverty, less likely to get an education and more likely to suffer bad health. And when they are born into poverty, it is much more difficult for them to lift themselves and their families out of it.

    Why? One reason is that breaking out of poverty takes time­and that is a resource women around the world are short on. On average, women spend about twice as much time as men in doing the unpaid work that makes life possible for everyone, like cooking, washing, cleaning, shopping and caring. In developing countries, the gap is even much bigger. As a result, women have no time to finish their education, learn new skills, open a business, develop personal relationships or even go to the doctor. They dream of creating a better future for their children, but they can not spare the hours to put those dreams that they have into action.

    The fact that the potential of so many women and girls is going unrealized is a sad thing­but it is also an opportunity for us. We need to recognize, reduce and redistribute the burden of work that is holding them back. Because if women have time to invest (投资) in themselves and their ideas, they could transform the world.

A group of small, waggling (扭动) robots that communicate by flashing lights can make collective decisions. This is similar to the process bees use to reach an agreement on where to build their nest.

"We believe that in the near future there are going to be simple robots that will do jobs that we don't want to do, and it will be very important that they make decisions on their own," says Carmen Miguel at the University of Barcelona in Spain. She and her team tested how copying bees might help with that.

When bees go house-hunting, they communicate their preferred locations through a "waggle dance". The more a bee recommends one location, the longer and harder it waggles. Eventually other bees join them, and they reach an agreement when a majority are waggling together. Researchers previously translated this behavior into a mathematical model, and Miguel and her colleagues used it to program decision-making rules into small robots called kilobots.

Each kilobot with three thin legs had an infrared-light emitter (红外线发射器) and receiver, and a colored LED light. Within a group, kilobots could move around, turn clockwise or anticlockwise and use infrared signals to exchange information.

Ezequiel Ferrero at the University of Barcelona says that across all the experiments, kilobots reached an agreement within about half an hour, even when they didn't have many immediate neighbors to communicate with. He says that getting the right combination of how long they spend transmitting their message and how much they walk around allowed them to make a collective decision in the end.