Five years ago, David Smith wore an expensive suit to work every day. "I was a clothes addict(有瘾的人)," he jokes. "I used to carry a fresh suit to work with me, so I could change if my clothes got wrinkled(有褶皱的)." Today David wears casual clothes (便装) to the office. He hardly ever wears a necktie. "I am working harder than ever." David says, "and I need to feel comfortable."

More and more companies are allowing their office workers to wear casual clothes to work. In the United States, the change from formal to casual office wear has been gradual. In the early 1990s, many companies allowed their employees to wear casual clothes on Friday. This became known as "casual Friday". "What started out as an extra one-day-a-week benefit for employees has really become an everyday thing." said business consultant Maisly Jones.

Why have so many companies started allowing their employees to wear casual clothes? "One reason is that it's easier for a company to attract new employees if it has a casual dress code." "A lot of young people don't want to dress up for work," says Owen Black, the owner of a software company, "so it's hard to hire people if you have a conservative (保守的) dress code." Another reason is that people seem happier and more productive when they are wearing comfortable clothes. In a study conducted by Levi Company, 85 percent of employers said that they believe that casual dress improves employee morale (心境, 士气). Only 4 percent of employers said that casual dress has a negative influence on productivity. Supporters of casual office wear also argue that a casual dress code helps them save money. "Suits are expensive, if you have to wear one every day," one person said. "For the same amount of money, you can buy a lot more casual clothes."

How to Study Smarter, Not Harder

    Here are some of our favorite study tips that will help any student study smarter, not harder:

Recite As You Study

    Reciting—saying things out loud should first take place as you read through each paragraph or section. Test yourself. This will help you to understand as well as learn faster because it is more active than reading or listening. It will also help you to notice your mistakes and the topics you have trouble understanding.

Take Fuller Notes

    Notes should be in your own words, brief and clear. They should be tidy and easy to read. Writing notes will help you better than just underlining as you read, since it forces you to rewrite ideas in your own words.

Study the Middle

    The best time to review is soon after you've learned something. You are more likely to remember the material at the beginning and the end of the lesson, so make sure you focus on the middle when you review.

Sleep On It

    Study before going to bed, unless you are very tired. It's easier to remember material you've just learned before sleeping than after an equal period of daytime activity, because your brain continues to think even after you've fallen asleep.

Combine Memory and Understanding

    There are two ways to remember: by memorizing and by understanding. Multiplication tables, telephone numbers, and math formulas are better learned by rote. Ideas are best learned by understanding.

    The more ways you have to think about an idea, the more meaning it will have; the more meaningful the learning, the better you can remember it. Pay attention to similarities in ideas and concepts, and then try to understand how they fit in with things you already know. Never be satisfied with anything less than a completely clear understanding of what you are reading. If you are not able to follow the thought, go back to the place where you first got confused and try again.

    Lucy, whose skeleton（骨骼） was discovered in Ethiopia in 1974, died shortly after she fell out of a tree, according to a new study published Monday in the British journal Nature.

    For their research, Kappelman and Dr. Richard Ketcham used a CT scanner to create more than 35,000 "slices" of Lucy's skeleton. Scientists named her Lucy from the Beatles song "Lucy in the Sky with Diamonds", which was played at the camp the night of her discovery.

    The following analysis of the slices showed sharp, clean breaks seen at the end of Lucy's right humerus （肱骨） are similar to bone breaks seen in victims of falls.

    The researchers concluded that these and other breaks in her skeleton show that Lucy, who is believed to have stood about 3 feet 6 inches and weighed about 60 pounds, fell feet first and used her arms to support herself﹣but that the injury was too severe to have been survivable.

    The researchers estimate that Lucy was going about 35 miles an hour when she hit the ground after falling from a height of roughly 40 feet, according to the statement.

    That sounds plausible. But other scientists are doubtful. "There are countless explanations for bone breaks," Dr, Donald C, Johanson, director of the Institute of Human Origins and one of the scientists who discovered Lucy, said, "The suggestion that she fell out of a tree is largely a just﹣so story and therefore unprovable." Johanson said it was more likely that Lucy's breaks occurred long after she died, saying that "elephant bones appear to have the same kind of breaks, It's unlikely they fell out of a tree.

    But the new research focused on "a small number of breaks" that are consistent with "high﹣energy bone﹣to﹣bone influences" and which differ from the sorts of breaks commonly seen in other collected bones. Kappelman responded in an email, "These appear to have occurred at or near the time of death."

Benjamin West, the father of American painting, showed his talent for art when he was only six years of age. But he did not know about brushes before a visitor told him he needed one. In those days, a brush was made from camel's hair. There were no camels nearby. Benjamin decided that cat hair would work instead. He cut some fur from the family cat to make a brush.

The brush did not last long. Soon Benjamin needed more fur. Before long, the cat began to look ragged(蓬乱). His father said that the cat must be sick. Benjamin was forced to admit what he had been doing.

The cat's lot was about to improve. That year, one of Benjamin's cousins, Mr. Pennington, came to visit. He was impressed with Benjamin's drawings. When he went home, he sent Benjamin a box of paint and some brushes. He also sent six engravings (版画) by an artist. These were the first pictures and first real paint and brushes Benjamin had ever seen.

In 1747, when Benjamin was nine years old, Mr. Pennington returned for another visit. He was amazed at what Benjamin had done with his gift. He asked Benjamin's parents if he might take the boy back to Philadelphia for a visit.

In the city, Mr. Pennington gave Benjamin materials for creating oil paintings. The boy began a landscape (风景) painting. William Williams, a well-known painter, came to see him work. Williams was impressed with Benjamin and gave him two classic books on painting to take home. The books were long and dull. Benjamin could read only a little, having been a poor student. But he later said, "Those two books were my companions by day, and under my pillow at night." While it is likely that he understood very little of the books, they were his introduction to classical paintings. The nine-year-old boy decided then that he would be an artist.

Researchers believe they have found evidence for a hidden ocean on Mimas, one of Saturn's major moons. This makes Mimas a target for learning more about the origins of life in our solar system. 

Saturn has 146 moons orbiting it. The biggest is larger than the planet Mercury; the smallest is roughly the size of a sports field on the Earth. Mimas, which was first discovered in 1789, is one of the major moons and is about 250 miles wide. 

Experts used to think Mimas was mostly made out of solid ice and rock. In 2014, astronomers noticed its orbit around Saturn was moving unsteadily. A shaky orbit can be caused either by a core shaped like a rugby ball or a huge liquid ocean beneath the surface. At first, lots of astronomers argued against the suggestion that Mimas had an ocean because there is no sign of it on the surface. 

To investigate more thoroughly, researchers looked at images taken by Cassini, a NASA spacecraft sent to study Satun. The images showed that the moon's orbit around Saturn drifted by about six miles over 13 years. The team's calculations found that the only way Mimas could move in this way is if it had a hidden ocean under the surface. They think the ocean formed when the moon's core warmed up and melted some of the ice. 

Mimas is just one of many moons that scientists think could have oceans below the surface Ganymede, which orbits Jupiter and is the largest moon in the solar system, has more water in its ocean than all of the oceans on the Earth. Titan, another of Saturn's moons, is believed to have a salty ocean beneath the surface. 

Space agencies want to study these oceans because they might be home to living organisms. However, the ocean on Mimas might not be old enough for life to have emerged there yet. It took hundreds of millions of years for life to develop on the Earth and the ocean on Mimas is relatively young;it is less than 25 million years old. 

It's widely recognized that play-based learning significantly benefits the cognitive, physical, social, and emotional health of children. Recent research suggests that certain board games, such as Chutes and Ladders and Monopoly, can further contribute to enhancing their mathematical abilities.

A team of researchers from Pontificia Universidad Católica de Chile in Santiago, Chile, reached this conclusion after a comprehensive analysis of 19 studies conducted between the years 2000 and 2023. With the exception of one study, all focused on the correlation between board games and the development of math skills.

In these studies, children aged between 3 and 9 engaged in board games under the watchful eyes of teachers or trained adults. The structured 20-minute gaming sessions were held twice weekly for a duration of approximately six weeks. In some of the studies, one group of children (the intervention group) played board games that were centered around numbers, while another group (the control group) played games that did not necessitate mathematical skills. In other instances, both the intervention and control groups indulged in number-based games, but they were assigned different games, such as Monopoly and Dominoes.

The mathematical proficiency of the children was evaluated both at the beginning and the end of each study. The researchers were particularly interested in observing improvements in four pivotal areas: the ability to name numbers and exhibit basic numerical understanding, for instance, recognizing that "nine is greater than three." They also monitored the children's progress in addition and subtraction, as well as their burgeoning interest in mathematics.

The findings of this study were published in the academic journal Early Years on July 6, 2023. The results indicated that engaging in board games positively influenced the children's math skills in more than half of the four key areas examined. Moreover, nearly a third of the children in the intervention groups outperformed their counterparts in the control groups on math assessments.

The researchers are optimistic that their findings will encourage the development of new board games specifically tailored for educational purposes in classrooms. In the meantime, consider enhancing your own mathematical skills by organizing a board game night with family and friends this summer—it all adds up to a fun and educational experience!