Scientists have always been interested in the high level of organization in ant societies. American researchers have watched ants build life-saving rafts to keep afloat during floods. They also have recorded how ants choose their next queen — the female whose job is to produce eggs.

    New technology is helping to improve researchers' understanding of the insects. But there is still a lot to be learned.

    Fire ants living in Brazilian forests are perfectly at home in an environment where flooding is common. To save themselves, the insects connect their legs together and create floating rafts. Some ant rafts can be up to 20 centimeters wide.

    David Hu is an engineer with the Georgia Institute of Technology, also known as Georgia Tech, saying, "If you have 100 ants, which means 600 legs, 99 percent of those legs will be connected to a neighbor. So they're very, very good at keeping this network. "

    David Hu and other Georgia Tech researchers wanted to study ants and the secret of their engineering. They froze ant rafts and then looked at them with the help of computed technology, or CT images. The pictures showed that larger ants serve in central positions to which smaller ants hold. The larger ants create pockets of air that keep the insects afloat.

    Scientists say small robots or materials that can change shape could be programmed in a similar way, working towards a shared goal.

    Researchers at North Carolina State University are also studying ants. They examined how Indian jumping ants choose the leader of the colony when they lose their top female or queen.

    While Black Friday and Cyber Monday help start the holiday shopping season, Giving Tuesday, which will be observed on November 28, attempts to inspire the season of giving. Now in its sixth year, the charitable(慈善的)day uses the power of social media to encourage organizations and individuals to donate funds or resources to worthy causes. Its mission is to bring positive change to communities through giving.

    Though devoting just one day to a worthy cause may not seem much, Giving Tuesday makes a surprisingly significant impact. In 2015,ORGANIZE,an online organ donor program asked people to “Give with your Heart”,by becoming registered donors. Thousands of Americans listen to the cry for help, resulting in one of the largest digital donor drives in US history.

    That same year, the Cleveland Library and the Pratt Library in Baltimore competed to see who could encourage more donations. While the Pratt Library won with a $41,000 acquisition, the Cleveland Library was able to raise a fairly large amount for its programs as well. In 2016, the University of Michigan encouraged students and friends to donate to hourly challenges. They raised an amazing $5.5 million! The university hopes to recreate the magic this year, with a virtual celebration to mark the institution's 200th anniversary.

    Giving Tuesday is not just a US phenomenon, but a global movement. In 2016, 98 countries participated in the event, raising $177 million, a 44% increase over 2015, when 71 nations collected $116.7 million. These numbers can only increase as the day gains further recognition.

    Though donating funds is a great way to help, there are numerous other ways to support your local community. You can give back by volunteering at a nearby nonprofit or food bank. Social media experts can do their share by spreading the information and inspiring their colleagues to get involved. Another great way to celebrate Giving Tuesday is by helping those closest to you, whether that's assisting a family member with chores or helping a neighbor with yard work.

    In areas like the Central United States that get lots of tornadoes, there^'s a common piece of celestial （天上的）fortune-telling that green skies mean a tornado is on its way. Research has shown that it isn^'t quite as simple as that, but scientists have found that if you see a green sky, you should probably go inside. As far as most scientists can tell, the green skies around powerful thunderstorms are usually a combination of red sunsets and water droplets.

    Daytime skies are blue because blue shorter wavelengths of visible light tend to bounce off （反射）air molecules better than red longer wavelength light. So the blue light gets bounced all over the sky and looks like it's coming from everywhere. Meanwhile, around sunset sunlight travels through so much atmosphere that just about all the blue is bounced away from the horizon, leaving all those reds and oranges behind. The sunset might look exclusively （独有的）red and orange, but there's still some green and even blue light hidden in there, just far less than the other colors. But for us to notice the remaining green light, it needs to hit something that reflects green light much better than red. That's where water comes in.

    Big tall threatening storm clouds are made of water droplets, and even though water is best at reflecting blue light, it can still reflect green pretty well, much better than reds and oranges, so under just the right conditions, the water in and around a cloud can bounce the green light hidden in the sunset right into our eyes making the sky look green.

    Still, none of the conditions that can turn skies green are unique to the clouds that produce tornadoes. Sometimes they just lead to lots of rain, and maybe some hail. So if you see huge storm clouds rolling in and a green tint （色调）in the sky, it doesn't necessarily mean there^'s about to be a tornado, but it does mean you should probably head indoors.

    What a day! I started at my new school this morning and had the best time. I made lots of new friends and really liked my teachers. I was nervous the night before, but I had no reason to be. Everyone was so friendly and polite. They made me feel at ease. It was like I'd been at the school for a hundred years!

    The day started very early at 7:00 am. I had my breakfast downstairs with my mom. She could tell that I was very nervous. Mom kept asking me what was wrong. She told me I had nothing to worry about and that everyone was going to love me. If they didn't love me, Mom said to send them her way for a good talking to. I couldn't stop laughing.

    My mom dropped me off at the school gates about five minutes before the bell. A little blonde (金发的) girl got dropped off at the same time and started waving (招手) at me. She ran over and told me her name was Abigail. She was very nice and we became close straight away. We spent all morning together and began to talk to another girl called Stacey. The three of us sat together in class all day and we even made our way home together! It went so quickly. Our teacher told us that tomorrow we would really start learning and developing new skills.

    I cannot wait until tomorrow and feel as though I am really going to enjoy my time at my new school. I only hope that my new friends feel the same way too.

Half a Day

    I walked alongside my father, holding his right hand. All my clothes were new: the black shoes, the green school uniform, and the red cap. They did not make me happy, however, as this was the day I was to be thrown into school for the first time.

    "Why school?" I asked my father. "What have I done?"

    "I'm not punishing you," he said, laughing. "School's not a punishment. It's a place that makes useful men out of boys. Don't you want to be useful like your brothers?"

    I was not convinced. I did not believe there was really any good to be had in tearing me away from my home and throwing me into the huge, high-walled building.

    When we arrived at the gate we could see the courtyard, vast and full of boys and girls. "Go in by you," said my father, "and join them. Put a smile on your face and be a good example to others."

    I hesitated and squeezed his hand firmly, but he gently pushed me from him. "Be a man", he said. "Today you truly begin life. You will find me waiting for you when it's time to leave."

    I took a few steps. Then the faces of the boys and girls came into view. I did not know a single one of them, and none of them knew me. I felt I was a stranger who had lost his way. But then some boys began to glance at me in curiosity, and one of them came over and asked, "Who brought you?"

    "My father," I whispered.

    "My father's dead," he said simply.

    I did not know what to say. The gate was now closed. Some of the children burst into tears. The bell rang. A lady came along and said, "This is your new home. There are mothers and fathers here, too. Everything that is enjoyable and beneficial is here. So dry your tears and face life joyfully."

    Well, it seemed that my misgivings had had no basis. From the first moments I made many friends. I had never imagined school would have this rich variety of experiences.

    If you could sail around the world with only one companion, who would you choose? Guirec Soudee, a 24-year-old man from France, chose his pet chicken.

    Soudee has been sailing around the world for two years. No matter which country he sails to, Monique, the hen, is by his side. He found her in the Canary Islands and knew right away they were meant to be best companions. "I didn't speak any Spanish and she didn't speak any French, however, we could always have a small talk, even though she didn't understand me." Soudee joked.

    He had always wanted a companion for his journey and originally thought about bringing a cat, before deciding it would be too much work to look after on a boat. Upon meeting Monique, Soudee realized a hen was the perfect choice. He believed they could communicate with each other well.

    Not only does it cost little to raise Monique, but she lays eggs as well — some things that are always a plus in a situation where storing a lot of food can be a challenge. She lays about six eggs a week on average, even in cold climates like Greenland, where Soudee and Monique are docked(进港) now.

    And what happens when the weather at sea gets bad? Usually Soudee lets Monique stay freely on the boat, but when the winds get terrible he ensures she is safe in her hutch so that she doesn't fall out of his boat and into the sea. Another thing Soudee must care for is the rule in every country he visits. They had met with customs officials in Canada. He was permitted to keep her, but he knows they might not always be so lucky.

    Although Monique can sometimes get on his nerves, Soudee says she's much better than a human companion aboard. "She follows me everywhere. All I need to do is shout 'Monique!' and she will come to me, sit on me, listen to my small talk and give me company," he said.

    After visiting Greenland, they'll head down the Bering Strait to Nome, Alaska. From there the destination is undecided, but Soudee will certainly discuss where they should travel to next with Monique.