When Nancy Flexer opened the door to her classroom near the end of her final school year, all 41 years of her career as a beloved first-grade teacher came to life right in front of her.

    Cole Elementary School in Tennessee surprised Flexer with a memorable and emotional retirement party featuring former students of all ages, dating back to the first class she taught in the 1973-74 school year. A video of the event shows an overwhelmed Flexer being moved to tears as she hears former students who are now adults tell her how much she affected their lives.

    "I'm one of the luckiest people in this world," Flexer said. "I remember I opened the door to the classroom thinking no one was in there, and it was wall-to-wall people and banners and everything. It was the coolest thing that could've ever happened in my life. How many times do we really realize the lives we've touched, the manner in which we've touched them, and that these are memories that stay with them for life?"

    Despite being young when they were taught by Flexer, students easily recalled the heartwarming notes she wrote them on report cards, the ways she helped them overcome shyness and awkwardness, and how she inspired them to future academic success to earn scholarships and advanced degrees.

Even though Flexer hadn't seen some of the former students for decades, she instantly remembered the names of every single one there.

    A scrapbook(剪贴簿) of her career was presented to her as one student after another recalled the effect Flexer had on his or her life.

    “I've had many opportunities to move to a school closer to my home, but I said 'Cole gave me so much in my life that when I retire, I will retire from Cole school and give back what's been given to me.” Flexer said. “My career could've taken me nowhere that would have made me happier. I think of it as a blessing.”

    I grew to be a tall girl but I tried to be as ordinary as possible. At school, I always chose a seat in the back of the room, and never raised my hand in class. When I was 16, I went to my new school. And I liked the English teacher. In my last year in high school, however, we were told that a new English teacher, Oliver Bascom, was going to teach us.

    Oliver Bascom! The girls laughed as we imagined a short and bald（秃头的）man．The situation was not funny, because this man would teach us for the whole year. Surprisingly, after we opened the door, there in front of the blackboard, we saw a young and handsome man!

    What followed was chaos, seventeen-year-old girls flying to get to seats in the front of the room. And I managed to get a front and center desk.

    I really wanted to make a good impression on my new teacher, but I usually kept quiet. The day that directions were given for our first major writing assignment, I arrived late to class. A friend later gave me the guidelines and I thought I understood them. I worked the whole weekend on the essay and waited nervously for Mr. Bascom's evaluation.

After three days, he arrived in class holding the corrected papers. "I've chosen the ten best essays for class discussion." he said.

    Twenty minutes later, my heart sank when he got to the last essay, and I didn't hear my name.

"These are all great essays," Mr. Bascom continued. "However, I am now going to read you the most successful of all…" We were all surprised as I was the author of this unusual work. A different girl walked out of the classroom that day. I knew that I had a new set of standards to live up to and that anything was possible in the future. Finally, I raised my head.

    Barbara McCintock was one of the most important scientists of the twentieth century. She made important discoveries about genes(基因) and chromosomes (染色体).

    Barbara McClintock was born in 1902 in Hartford, Connecticut. Her family moved to Brooklyn area of new York City in 1908.Barbara was an active child with interests in sports and music. She also developed an interest in science.

    She studied science at Cornell University in Ithaca, New York. Barbara was among a small number of undergraduate students to receive training in genetics in 1921. Years later, she noted that few college students wanted to study genetics.

    Barbara McClintock decided to study botany, the scientific study of plants, at Cornell University. She completed her undergraduate studies in 1923. McClintock decided to continue her education at Cornell. She completed a master's degree in 1925. Two years later, she finished all her requirements for a doctorate degree.

    McCintock stayed at Cornell after she completed her education. She taught students botany. The 1930s were not a good time to be a young scientist in the United States. The country was in the middle of the great economic Depression. Millions of Americans were unemployed. Male scientists were offered jobs. But female geneticists were not much in demand.

    An old friend from Cornell, Marcus Rhoades, invited McClintock to spend the summer of 1941 working at the Cold Spring Harbor Laboratory. It is a research center on Long Island, near New York City. McClintock started in a temporary (临时的) job with the genetics department. A short time later, she accepted a permanent (永久的) position with the laboratory. This gave her the freedom to continue her research without having to teach or repeatedly ask for financial aid.

    By the 1970s, her discoveries had had an effect on everything from genetic engineering to cancer research. McClintock won the Nobel Prize for Physiology or Medicine in 1983 for her discovery of the ability of genes to change positions on chromosomes. She was the first American woman to win an unshared Nobel Prize.

    When we see cute babies, or adorable baby animals, many of us feel a strong urge to squeeze or pinch them or even bite them. Scientists call this strange response "cute aggression".

    Stavropoulos's team gathered 54 people to look at 32 pictures of four sets. One set contained photos of cute baby animals. Another set contained pictures of less-cute, fully grown animals. The other two sets were photos of human babies which were digitally edited. One set was changed to emphasize features we find cute, such as big eyes and full cheeks. The other was edited to reduce those features.

    The scientists found that the participants had much more feelings of cute aggression towards images of baby animals than those of adult animals. Surprisingly, this difference was not seen from the two sets of human baby pictures in comparison.

    To assess cute aggression, the participants were asked questions about the degree of wanting to aggress the subjects of the photos, and of wanting to care for them. Scientists suspect these responses are associated with not only the brain's emotional systems, but also its reward systems, which adjust motivation, pleasure and feelings of "wanting".

    Cute aggression may give humans the highly adaptive ability to control emotional response. To limit the motivation of positive feelings, the brain gives commands of the aggression. In other words, the brain throws in a bit of aggression to keep the good feelings from becoming uncontrolled. "If you find yourself fascinated by how cute a baby is, —so much so that you simply can't control it—that baby is going to starve." It stops us from investing too much energy into cute things. So, there is no need to feel bad for the desire to pinch them at the sight of cute babies. It's not because we're mean people. The "unfriendly" movement of our fingers is just our brain's way of making sure nothing gets too cute to handle.

    Dogs certainly need to bark (犬吠) every now and then, but if your neighbor's dog is getting in the way of your daily life, you need to do something.

    "Before you take action, you should record the dates and times that the barking happens to find out any patterns," says Schweitzer, who is a dog owner. You might notice the barking only happens when the owners are at work, or during thunderstorms.

    After two to three weeks of observing (观察), go to your neighbors with the facts. Wait for a time when the barking is over. "Since you're trying to keep a good relationship, you can't go when you're angry and upset," says Schweitzer. Besides, your neighbors might not even realize the barks are a problem, especially if the worst barking happens when they're not at home.

    Politely explain the times when the barking gets bad, and then suggest a way of solving the problem. Ask if the dog can stay inside during storms, or offer a dog training class.

    Making friends with the dog could help you gain some peace and quiet. If your neighbors introduce you to their dog, you should give the dog a treat. "If they become more comfortable seeing you, they're less likely to bark when they see you or when they're in the backyard，" says Schweitzer.

    Whatever you do, don't talk with your other neighbors about the problem or start a petition (诉状) to get the dog to quiet down. "Those make people feel angry," says Schweitzer. "That's when things escalate."

    If weeks go by and you still aren't seeing a difference, follow up with a note. Tie a dog treat on the note to build trust with your neighbors, and make a copy before dropping it off. That way, you'll have evidence (证据) that you've discussed it before and followed up politely if you need to bring in a third party, says Schweitzer.

    The Chinese invented paper in 105 A. D. They mixed the bark of a tree and rags (破布) with water, put a screen into the mixture, and lifted out a thin piece of wet paper. They dried the paper in the sun.

    The Chinese kept their secret of how to make paper until a war with Muslims in the ninth century. The art of papermaking soon spread throughout the Muslim world.

    The Mayan Indians in Central America and Pacific Islanders also discovered how to make paper, but their knowledge never spread to the rest of the world.

    For centuries, all paper was made by hand. Rags were the main material. Then a French scientist discovered that people could make paper from wood, too. Finally, in the eighteenth century, a Frenchman invented a machine to make paper from wood.