【推荐1】As your alarm clock rings, you slowly open one eye. It seems like it was only a few hours ago that you finished your homework. You close your eyes for just five more minutes, but then your mom knocks on the door. “Time to get up, or you’ll miss the bus!” she says.

If this sounds familiar, you’re not alone. According to a survey, nearly 60 percent of middle school students in the U. S. aren’t getting the recommended 8.5 to 9.5 hours of sleep a night.

How does it happen? In fact, starting the school day too early can take away much-needed sleep from teenagers. Studies show that well-rested teenagers are more likely to get good grades and less likely to suffer from depression (抑郁). Besides, teenagers fall asleep later at night by nature. As a result, some students may only get as few as five hours of sleep.

Many people have realised the importance of enough sleep. Schools in several states have changed to later start times in recent years. In New Jersey, a group of students have formed an organization called Later School Start Times. It wants local middle schools to start 30 minutes later.

▲ Many schools say later start times would create a number of problems. There’s a worry that some kids will walk back home in the dark if the school starts later. It will also leave teens with fewer hours for after-school activities and homework. That’s what Erin Isherwood, a parent from California, is worried about. “My son has an exercise class that he really loves at a gym right after school,” she says. “Now he can’t go.”

Considering the advantages and disadvantages of later school start times, it seems a hard choice to make. The early bird catches the worm (虫子). But what if the bird is too sleepy and tired to catch one?

【推荐2】Have you ever heard of the term “biodiversity(生物多样性)”? It may sound like a difficult scientific term, but it’s actually an important idea of environmental protection that we should all know well. Let’s find out why biodiversity is so important.

Biodiversity helps the balance of the ecosystem(生态系统).

Each species(物种) plays an important role in the ecosystem, and the loss of even one species can have a great effect on the whole ecosystem. For example, if a certain kind of insect was to disappear, the plants depending on that insect would also be in danger. Then the plants will in turn influence the animals who depend on those plants for food.

Biodiversity is important for human health.

Many modern medicines come from plants and animals. For example, Taxol, a medicine used to treat cancer, was first extracted(提取) from the yew(紫杉) trees. If these species were to disappear, we would lose the chance to discover new medicines.

Biodiversity is important for cultural reasons.

Many cultures around the world have traditions and beliefs that are tied to the natural world. For example, the Maasai people of Kenya and Tanzania have a deep respect for the wildlife, and their culture is closely connected with the natural world.

So, what can we do to protect biodiversity? One important step is to reduce our effect on the environment. This can include things like reducing our use of single-use plastics, saving water and reducing the emission(排放) of CO. By doing these, we can help protect biodiversity and our planet for the future.