2 . The Maya city of Tikal is famous for its amazing palaces and temples. But something far more ordinary kept Tikal functioning: its water-purifying(净化) system, the earliest known of its kind.

Researchers recently discovered a volcanic mineral that traps microbes(微生物) and heavy metals in Tikal's largest reservoir(水库). Because the material is not found nearby, the finding suggests the presence of a man-made water-purifying device.

The finding denies the long-standing idea that the ancient worlds technological achievements belonged to the Eastern world, like Egypt, and China. The leading scientist of this research, Kenneth Tankersley says, “When talking about purifying water, the Maya were thousands of years ahead.”

Located in the forests of Central America, Tikal, is thought to have been home to more than 45,000 people. They had to struggle against a dry season lasting from November through April. Storing water in reservoirs was a solution, but that water had to be fit to drink, said Kenneth, “Keeping water clean was of great importance.”

A few years ago, the researchers were surprised to find that the largest reservoir, Corriental, had significantly fewer harmful chemicals than the others. “The water quality at Corriental was much higher.”

Somehow the Maya must have been purifying Corriental’s water, the team assumed. “The Maya used gardens as their bathrooms.” Kenneth said, “The water coming into the reservoir would not have been very clean.”

At the bottom of Corriental, scientists found four separate layers(层), each a few centimeters thick, of millimeter-scale “zeolites(沸石)”. This type of volcanic mineral can purify water and is still in widespread use today, Kenneth says, “Just about everything we drink, from bottled water to wine, runs through a zeolite purifying device.”

The Maya wouldn’t have known about the zeolite in rock, but they would have recognized the purifying effects, the researchers suggest. A zeolite-rich rock formation about 30 kilometers northeast of Tikal is the likely source of the material in Corriental reservoir, the team said last month in Scientific Reports. Water at this site “was clear and tasted good.”

3 . A 15-year-old Colorado high school student and young scientist who has used artificial intelligence (AI) and created apps to address polluted drinking water, drug addiction and other social problems has been named Time Magazine’s first-ever “Kid of the Year”.

Rao told The Associated Press in an interview from her home that the prize is nothing that I could have ever imagined. And I’m so grateful and just so excited that we’re really taking a look at the upcoming generation and our generation, since the future is in our hands.

Time said Rao stood out for creating a global community of young innovators and inspiring them to pursue their goals. Rao insisted that starting out small doesn't matter, as long as you're passionate about it.

She told Time contributing editor Angelina Jolie in an interview that her science pursuits started early as a way to improve social conditions. The drinking water crisis in Flint, Michigan, inspired her work to develop a way to detect pollutants and send those results to a mobile phone, she said.

“I was like 10 when I told my parents that I wanted to research carbon nanotube (纳米管) sensor technology at the Denver Water quality research lab, and my mum was like, A what?” Rao told Jolie. She said that work is going to be in our generation’s hands pretty soon. “So if no one else is gonna do it, I’m gonna do it.”

In a world where science is increasingly questioned or challenged, Rao insisted that its pursuit is an act of kindness, the best way that a younger generation can better the world.

“We have science in everything we’re involved in, and I think that’s the biggest thing to put out there, that science is cool, innovating is cool, and anybody can be an innovator.” Rao said, “Anybody can do science.”

4 . The Internet is a growing new world that has been developing ever since it was created many years ago. The only reason Internet sales are not taxed（征税）is because we did not know the Internet would be used to sell products when it was created. Internet sales are no different than going into the store to buy the exact same product except for the fact that Internet sales are not taxed.

When buying online， people cannot see and touch the product the same way they could in a store. To fix this， customers are going into the store to see the product. Then if they like the product， they buy it online to save money on the sales tax. This is a form of tax evasion（逃税）if you ask me！

Everyone has to pay the tax in the store so they should have to pay taxes online as well. Also，the added money brought in through Internet taxing could help the government to fund certain policies and other things that they could not do without the added funds. This could go toward the country's schools or other things necessary for society to function well. These funds could be extremely beneficial because of the recession（经济衰退）that the country is in at this point. Internet taxing is a way to increase those funds and in turn improve the quality of life for all who live in that country.

In conclusion， there are many more positives than negatives in the argument over taxing Internet sales. I do understand that I may have to pay more if I want to buy something online， but the funds stay within my society and help my country. The added cost may hurt me at first but in the end， the funds will help me and others in our country.

5 . Here at VOA Learning English, we love to help those who teach English make learning more interactive, student-centered and fun. Besides our quizzes, downloadable lesson plans and other materials, there are other creative ways to use our programs in your classroom. Let’s start with speaking activities.

Beginners: Using the Day in Photos

Every day, VOA Learning English posts fascinating photos from around the world. We call it the Day in Photos.

Here’s a speaking activity that will inspire even the shyest beginning speakers to talk to their classmates. With students sitting in pairs, show an image on the screen. Have one student describe what she sees in the image. Then, have the other student imagine what the people or animals in the photo are thinking or saying.

Intermediate（之间的）learners: Using Learning English TV

Learning English TV features two-minute videos on topics from science to politics to health. For intermediate learners, you can use pair work to have students make a summary of what they learn after watching the videos.

Advanced learners: Using Learning English TV

For this level, have students do the activity exactly as they did in the intermediate activity, but ask students to come up with three questions on additional things they’d like to learn about the topic. You can also use our video series America’s Presidents to set off discussion on debatable topics. Students can work in small groups to express their opinions on what they watched in the video.

Advanced learners: Using English at the Movies

These short series explore an idiom, or common expression.

Students can use the context（上下文）of the movie clip and its explanation-based on the multiple choice quiz in the video-to develop their understanding of the expression.

One fun activity is to have students create two-or three-person dialogues using the new idioms. They can act out or voice the dialogues in their groups or share the dialogues with the whole class.

6 . Some teens are disapproving of compulsory BMI (body mass index) （身体质量指数） checks in PE classes. Do BMI checks at school do more harm than good? Two teens take sides.

Maya Meade, a high school freshman in Ohio, says yes. “I understand that schools want to weigh students because they are concerned about their physical health. That’s not a bad thing! But what about their mental health? For many students, appearance and self-image are huge sources of stress. Forcing teens to be weighed at school will only increase the pressure they feel to fit a certain mold (模子)”, says Maya.

In Maya’s opinion, weight is a personal matter that should stay between a doctor and a patient. She says, “Just imagine someone who struggles with body image being told that his or her BMI is too high as classmates look on! Even if other kids can’t hear, no student wants to feel judged by his or her teacher. That’s not why we go to school.”

Maya thinks if a school wants to have an impact on a student’s physical health, there are better ways to do it, such as providing healthy but filling meals, encouraging physical activity and teaching students about nutrition.

Ben Bagbek, a second-year student in a high school in New York, holds a different opinion. “There is no reason why a school should not be allowed to weigh its students and teach them how to calculate BMI! Obesity (肥胖症) is a huge public health concern in our country. And schools are in a position to help students understand what their weight means to their health -- before they’re at risk of life-threatening conditions.”

“A school’s job is to help students reach their full potential, and your health undoubtedly plays a role in your academic performance. BMI is not a perfect measurement, but it can help you identify the need for healthier eating habits or more physical activity.” says Ben.

The bottom line is: When you feel good, you learn better. As long as the actual number on the scale stays private, it should be viewed as an important part of your health education.

7 . A rainforest is an area covered by tall trees with the total high rainfall spreading（扩大） quite equally through the year and the temperature rarely falling below 16°C. Rainforests have a great influence on the world environment because they can take in heat from the sun and adjust the climate.

Without the forest cover, these areas would reflect（反射）more heat into the atmosphere, warming the rest of the world. Losing the rainforests may also influence wind and rainfall patterns，potentially（潜 在地） causing certain natural disasters all over the world.

In the past hundred years, humans have begun destroying rainforests in search of three major resources ： land for crops, wood for paper and other products, land for raising farm animals. This action affects the environment as a whole. For example, a lot of carbon dioxide in the air comes from burning the rainforests. People obviously have a need for the resources we gain from cutting trees but we will suffer much more than we will benefit.

There are two main reasons for this. Firstly, when people cut down trees, generally they can only use the land for a year or two. Secondly, cutting large sections of rainforests may provide a good supply of wood right now, but in the long run it actually reduces the world’s wood supply. Rainforests are often called the world's drugstore. More than 25% of the medicines we use today come from plants in rainforests. However, fewer than 1% of rainforest plants have been examined for their medical value. It is extremely likely that our best chance to cure diseases lies somewhere in the world’s shrinking（减 少）rainforests.

8 . The following are some good shows on Netflix right now. Figuring out what to watch this month has never been easier.

New Girl

For a good show on Netflix that will put you in a great mood with every episode, turn to this comedy, which follows the girl as she moves in with three quirky(古怪的)men. Their seven seasons of dishonest activities will keep you entertained for hours— a close — to — perfect way to spend your time indoors.

Community

Finally available on Netflix, this beloved 2010s comedy about a group of students at a   community college is one of the best TV shows to watch. It'll keep you entertained for days.

Queer Eye

This emotional, insightful reality series follows five men as they help people improve their lives. The five famous stars have become personalities in their own right and watching them on-screen together is one of the best parts of the show, but seeing how they help and encourage the people they work with is sure to warm even the coolest heart.

One Day at a Time

A remake o£ a TV classic, this family-first series follows a newly single mother as she raises her children. Her traditional Latina mother (played by Rita Moreno)takes a starring role as the family faces puberty(青春期)，young love, life milestones, and more together. With its own fan following, this three-season series is the perfect settle — in — together — and — watch show.

9 . When you go for a run outside, chances are that you’ll find litter all around you. Do you just go past it, or do you stop and pick it up? If you choose the latter, you’re part of the latest fitness trend that’s sweeping the West: plogging.

The word “plogging” combines the Swedish phrase “plocka upp” (pick up) with the English word “jogging”.

Running – especially marathons – is often associated with good causes. And plogging, which combines environmentalism with fitness, has become the new poster boy for the environmentally-friendly runner. All a plogger needs is a trash bag, and ideally a pair of gloves to protect their hands.

The process of collecting garbage is simple, but it sheds light on serious environmental issues. “When I usually walk through the streets of New York, the sight of newspapers, lost hats, and shattered glass doesn’t bother me,” Matthew Sedacca of Men’s Health magazine wrote. “But when I was plogging and focused on trash collecting, the amount of garbage strewn (散布) across the sidewalks and along the pavement was kind of shocking.”

While collecting garbage, ploggers learn to classify and dispose of it correctly too. Laura Lindberg, a plogger who lives in New Jersey, US, always keeps a note of what she’s collected in her mind. This way, she knows what can stay in her trash bag and what can go in a nearby recycling bin.

It may be difficult to measure the sense of self-satisfaction that comes from making the world a cleaner, greener and more beautiful place, but the health benefits of plogging are easy to see. According to the Swedish fitness app Lifesum, a 30-minute plogging burns around 288 calories, compared to 235 calories burned from just jogging.

So the next time you go out jogging, why not carry a trash bag and collect some litter along the way? Your body and the environment will thank you.

10 . The clock always seems to be ticking rather too fast in the doctor’s office and the queue of patients outside the door seems to be pressing rather too hard. Some say it’s high time for the model of short, sharp one-to-one appointments to give way to shared medical appointments (SMAs).

SMAs are doctor-patient visits in which a group of patients receive patient education and counseling (咨询), physical examination and medical support in a group setting. Typically, SMAs are designed to have one or more doctors attend to a group of patients who share a common illness or medical condition. In contrast to one-to-one visits, SMAs provide a longer appointment time-frame as well as the opportunity for patients to have improved access to their physicians and meanwhile pick up additional information and support from peers.

However, doctors who have pioneered the shared appointment approach report that there are significant challenges involved. Dr. Sumego, director of shared medical appointments, Cleveland Clinic, identifies culture change as the most significant challenge. Physicians and nurses are trained in a model of personal service and privacy; the SMA approach is a fundamental challenge to those fixed ideas. They need shared goals and a way of testing the innovation against agreed standards. Dr. Sumego says, “The physicians may be worried about the possible chaos and efficiencies that are marketed. They also have to make the patients understand what their appointment is, and what the expectation is.”

“So, if an organization was looking to start shared medical appointments, I would advise them to start the buy-in from a few champion physicians, develop the work-flow and develop some experience. Provide some support behind what that best practice should look like. Create some standards so that, as the concept spreads, you can employ that experience to start the next shared medical appointments and the next.”