Friendship is often about action. It's about what we do together, how we treat each other. The key to friendship is kindness. 

Best friends are nice, but the word “best” can make it feel like a contest. Most people have different friends and for different situations. So it’s okay to have several close friends instead of needing to identify just one best friend.

Some people have lots of friends, but other people may just have a few close friends. People with more friends tend to put more effort into having more friends. It’s okay to have a lot of friends or just a few! 

To make friends, you have to show an openness to friendship. That can be as easy as smiling or saying hi. It’s also important to be kind to potential friends. And it also helps to identify people who have similar interests to you. Then, invite them to do something. Kids make friends by doing fun things with other kids. Don’t wait until you feel close to someone to invite them to do something; you become close by doing shared activities.

Shy people might be unintentionally sending the message to potential friends that they don’t like them. Stop focusing on being uncomfortable and instead look the other kid in the eye (or the forehead if eye contact is hard for you), smile and say hello. Practice it with an adult. 

At recess or on the playground, bigger groups of kids will be more open to you joining than groups with just two or three kids. 

Research shows that instead of asking if you can play with a big group, hang back and watch for a few minutes to figure out the game the other kids are playing, and then just join in. If you ask “Can I play with you?” you risk interrupting the play. 

Bullying is deliberate (intentional) meanness directed at one person where there is an imbalance of power. For example, an older or more popular kid picking on a younger or less popular kid. 

It’s important to know the difference between bullying and meanness. Bullying requires adult intervention. If you’re having a problem with a friend that is not bullying, you may still want to talk that through with an adult, but it’s often possible to handle that conflict with your friend on your own. 

There are over 9,000 known species of crickets on the planet. These insects are best known for singing and hopping!

Insects are divided into different orders depending on what kind they are. Crickets are in the order known as Orthoptera, which contains grasshoppers, locusts, crickets and bush crickets, and katydids.

Crickets and grasshoppers are different! For one thing, most grasshoppers make noise by rubbing one of their legs against one of their wings. But most crickets make sound by rubbing their two forewings (their front wings) together. One wing is jagged, like a little row of teeth. And the other wing kind of scrapes up against it, making a sound.

The number of teeth on the scraper, the speed of the rubbing and how frequently they make the chirps differ depending on the species. So there are lots of different cricket songs.

Try an experiment: Get a comb and run your fingernail across it. See if you can make a sound. If you have more than one comb, or a comb with two differently sized/spaced teeth, see if they make different sounds. Does the size of the fingernail make a difference in the sound? Try giving your comb to an adult and find out!

In most cricket species, the males chirp to attract a female. And they mostly sing at night to help avoid predators. 

But Karim Vahed says some studies have shown that predators like domestic house cats follow the chirps of the crickets to find and eat them!

Imagine a cricket the size of a hamster! A cricket so big it would cover the palm of your hand if you were holding it. The giant wētā [say it: WEH-tah] is that insect!  There are several species of giant wētās. They all live in New Zealand and most of them are protected because they’re quite rare.

Insects are the most diverse group of animals on the planet. There are more than a million known species (about 80% of all known animals). But scientists estimate anywhere from 10 million to 80 million insect species have yet to be discovered!

Three pandas live at the National Zoo: adults Tian Tian and Mei Xiang and their cub, Xiao Qi Ji. 

Zookeepers are never in the same space as the pandas. Even though they are herbivores, pandas are still wild animals with sharp claws and big teeth, so it’s important for people to stay safe.

Researchers at the National Zoo have worked with colleagues in China on a breeding program for both captive and wild pandas. That research has helped pandas go from endangered to vulnerable. They’re still at risk of extinction, but doing better than they were just a few decades ago.

Pandas eat 100 pounds of bamboo per day! The National Zoo cuts bamboo from sites around the D.C. area, including at some local private homes.

Researchers aren’t sure why pandas are black and white, but the leading theory is that the white color provides camouflage in their snowy natural habitat and the black fur helps them blend in when they hide in shady bamboo forests. Panda cubs do have predators in the wild.

Pandas do not hibernate, but they spend their time eating or sleeping. They have a period of deep sleep, similar to the torpor of reptiles. Keepers say they try not to wake sleeping pandas because they get very grumpy! (So the saying, “Never wake a sleeping bear” is especially true for pandas.)

Zoo pandas get daily training to make their care easier. For example, they learn their names and they are taught to open their mouths and show a paw so they can more easily receive medical care.

Zoos used to display animals primarily for human enjoyment. Now, most zoos focus on species conservation, research and educating the public about animal species. 

Climate is the long-term trend of temperatures and weather. You can think of the difference between climate and weather like a dog walking down a sidewalk: The dog might go from side to side of the sidewalk - that’s kind of like the weather - it varies. But the general direction of the dog is forward - that’s the climate.

Since the 1800s we’ve had a lot of changes in technology that mean humans are burning a lot of fossil fuels like oil, gas and coal, to power engines, run our cars, heat our homes and create electricity. That puts a lot of greenhouse gasses and carbon dioxide into the atmosphere.

The atmosphere is like a blanket around the earth. The increase in greenhouse gasses means that the blanket is getting thicker, making the earth warmer.

Think of the earth like a human body: when a fever increases our body temperature by a few degrees, it can make you feel really sick (sometimes really hot, but other times with cold shivers). It’s the same thing for the earth! Even one or two degrees difference in average global temperature can make a big difference, including changing the amount of rainfall that a region gets or the overall temperature of the ocean, throwing our systems out of balance.

Climate change can increase sea levels. As polar ice caps melt because of increasing temperature, the water levels rise, which can cause higher tides and more flooding. A good experiment you can do to visualize this is to grab a mixing bowl and turn a smaller bowl upside down inside of it (like an island). Pour some water and several ice cubes into the big bowl and see how high the water goes up the side of the smaller bowl. (You might need to weigh the smaller bowl down so it doesn’t float up.) As the ice melts, observe how the water level rises up the sides of the small bowl.

Increased water temperatures are bad for coral reefs and other ocean animals.

The best way to stop climate change is to stop burning fossil fuels.

People will respond to climate change through coping mechanisms, including migration and relocation.

The people most affected by climate change are the people least responsible for greenhouse gas emissions.

If you’re concerned about global warming, find ways to consume fewer resources and to burn fewer fossil fuels. And lobby your government officials to make policies that benefit the environment and those most vulnerable to climate change.

New seeds are made through pollination, plant reproduction. Pollen makes its way to the ovary of a flower in various ways. Sometimes it is spread from one flower to another by a pollinator, like a bee or hummingbird. Some flowers are called “perfect”, meaning they can reproduce with their own pollen–not the pollen from another plant. But they still need a way for their own pollen to drop onto their egg. A gentle gust of wind, or the jostling of the plant by a gardener's hand can do the trick. 

The flower will create the seed and then the flower structure will fade, leaving behind a seed. Sometimes it’s in a pod, sometimes it’s in a fruit or other structure to protect it. 

Seeds are alive, but dormant. They contain all the nutrients needed to make a new plant. That seed will wait for the right conditions to germinate and create a new plant. Some seeds only need a little moisture to germinate, others need to be submerged in water. There are many different kinds of seeds and they have different necessary conditions.

Flowers can be many different colors. They use those colors to attract pollinators. Those colors are created by pigments, natural colorings, in the plants.

Some plants only flower once per year, others can bloom multiple times. Some plants flower in spring, others in summer, and some in fall.

There is a lot of diversity in plants and the way they reproduce. That benefits all of us because if some plants aren’t thriving in certain conditions, other plants may do better. 

Why do we prefer one hand over the other? McManus says it probably pays to specialize. It’s better to do something with one hand over and over and get really good at it, as opposed to doing it sometimes with one hand and sometimes with the other. For example, it takes years to develop your handwriting, so it would take twice as long to develop good handwriting with both hands!

How do we pick which hand? We chose the hand that feels more normal to us, and then we practice with that hand. Try a simple experiment: bring your hands together quickly and entwine your fingers like you’re holding hands with yourself. Which thumb do you have on top? Now switch which thumb is on top. It probably feels a bit wrong.

90 percent of people use their right hand more. Our brain is asymmetrical (different on the right and left sides), and most of us use the left half of our brain to talk. Our heart is also on the left side of our body for most humans and vertebrates.

There must be an advantage to being left-handed or we wouldn’t have left-handed people, but no one is sure exactly what that advantage is.

What about people who say they’re ambidextrous? McManus believes there’s no such thing. He says people who say they’re ambidextrous are generally good at different things with each hand, but aren’t actually equally good at everything with both hands. McManus calls these people mixed-handers.

Many animals also have handedness. But while right-handedness is dominant i people, animals tend to split down the middle. (So, for example, half of cats are right-handed, half are left-handed. Same goes for dogs and mice etc.

in the 19th century, when people wrote with pens dipped in inkwells, writing with your left hand was messy business, as left hands would smear ink across the page. But as people have shifted to mostly typing, the hand you write with matters less.

For every five left-handed boys, there are only four left-handed girls, and scientists have no idea why.

Bioacoustics is the study of sounds made in nature. Scientists like Elodie Briefer study how animals make sounds and what information we can find in those sounds. Scientists will record sounds and use computers to measure and analyze what they hear and use observational skills to help determine what the sounds might mean.

Animals speak in emotion, not in words. Pigs have contact calls as well as positive and negative calls. Researchers have found that pigs will make longer calls when they are unhappy. Scientists and animal welfare advocates hope to use this information to eventually develop an app that farmers can use to improve animals’ lives on farms.

With words like moo, oink and cockadoodle-do, we are giving a name to a sound. But we’re not just trying to mimic the sound. Most of us can make the sound of a pig snort but we need words like oink because we don’t want to stop using our language to make a pig snort in the middle of a conversation.

Human voices are capable of millions of sounds but a language only uses a subset of those sounds. Our animal noise words will use the sounds available in our individual languages.

Words that sound like the sound they are describing are called onomatopoeia.

An animal has to have some cultural importance for a language to create a word for its call. That’s why we don’t have words in English for the noise a camel or a sloth would make. In Turkish there is no word for a pig call because that culture doesn’t keep pigs on farms.

We can see the moon during the day for the same reason we see the moon at night. The surface of the moon is reflecting the sun's light into our eyes. But we don't see the moon all the time during the day, and that's because of where the moon might be in the sky. There are times where the moon is on the other side of the earth so we can’t see it. We see the moon in the sky when it’s in the right spot and it’s reflecting enough light to be brighter than the background of the sky.

The moon is a satellite. A satellite is something that moves or rotates around a planet, the earth in this case. The moon is 239,000 miles away. That's far, but it's way closer than any of the other stars or planets you can see in the night sky. That's why the moon looks so big compared to other celestial objects even though the stars are actually much bigger.

The moon weighs 100,000,000,000,000,000,000,000 pounds. That’s a lot! But it’s such a big number it’s hard to imagine how much that weighs. Instead, think about how much the moon weighs compared to the Earth. It turns out that the moon is about 1% percent the mass of the earth. That’s a lot!

When you’re in a car and it feels like the moon is following you, what you’re actually seeing is an optical illusion. The moon is very far away, compared to anything else you see when you're driving — like the telephone poles that appear to fly past your car as you're going down a highway. But the moon is so far away that its size and shape in the sky doesn’t change, so it feels like the moon is following you.