Level 3: Explorers (Age 11–14, Grades 6–8)
Mountains form some of the most spectacular landscapes in the world. In the highest mountains, huge peaks with steep sides are separated by deep valleys, cut by ice or fast-flowing rivers. Mountainous areas make up around a quarter of the land surface and are found across all continents.
Aging is a fact of life. Even if you avoid bad accidents, injuries, and infections, you won’t stay healthy forever. Your body will break down as you get older. You’ll get wrinkles and achy joints. Your vision and hearing will fade. Your chance of developing cancer, heart disease, and many other ailments will greatly increase. Aging “bedevils us all,” writes Steven N. Austad in his book, Methuselah’s Zoo. He defines aging as “the progressive deterioration over time of bodily functions and defenses along with increasing susceptibility to diseases.”
关于衰老，动物教会了我们什么 Continue reading »
No stars . No planets . Not even any atoms . At the moment of its birth, the universe was emptiness. Then, in a burst of inflation—a bit like a balloon blowing up—a very tiny area grew much, much larger. This happened when the age of the universe was just “a trillionth of a trillionth of a trillionth of a second”, says Alexei Filippenko. He’s an astronomer at the University of California, Berkeley. The dramatic period is extremely brief. During inflation, the universe’s size doubled around at least 100 times.
In November 2014, LeeAnne Walters turned on the tap in her kitchen in the city of Flint, Michigan. Disgusting, brown water streamed out. Over the following weeks, its color ranged from “light yellow to nasty, dark-looking
cooking grease,” she recalls.
污染水—弗林特河与公共健康危机的故事 Continue reading »
Welcome to the year 2050. In cities around the world, cars whiz past tall buildings and factories, yet the air is clear, clean, and cool. People have stopped burning coal, oil, and gas to run engines or make heat and electricity. These fossil fuels no longer spew pollution and greenhouse gases into the air. As a result, climate change is slowing. Dangerous wildfires, hurricanes, and other natural disasters are becoming less common. Humanity has managed to back the world away from the brink of disaster.
2050年，我们将用什么来替代化石能源？ Continue reading »
“Everyday, theWorld Mind churns out new inventions. It cures diseases,finds new ways of making things,builds new robots andother machines, and even creates new forms of art, music, drama, and sport. It hasslowly reversedclimate change, backing Earth away from the brink of environmentaldisaster… The World Mind protects all the animals and plants in the world and has foundways to make and distribute food,clothing,andshelter so that no one experiences poverty. It has built and launched starships to explore the galaxy. It has also established societies and governments that keep everyone at peace. War belongs to thedistant past. “
Young people’s bodies change during adolescence. Their thinking and reasoning skills change. And their relationships with others change as well. Changes in relationships are a normal and natural part of growing up. Yet those relationships can sometimes be confusing.
As you’re learning, there are many amazing techniques available to modern archaeologists. These involve detailed study of small areas of ground, but how do people know where to start looking in the first place?
Do you want to visit Mars? Someday, you may get a chance. Several countries and companies have plans for crewed missions to Mars. Elon Musk, a famous inventor and founder of the company SpaceX, is planning one of those missions for 2026. But he has even bigger visions. In a 2021 speech, he said that he wants to “build a city on Mars to become a spacefaring civilization, a multi-planet species. ”
