But Why: A Podcast for Curious Kids

How do popcorn kernels pop? How do salmon know where to return to spawn? How do rabbits change colors? Why does television fry your brain? How do zippers zip stuff? Who was the fastest runner in the world? In this episode, we'll tackle all of these questions! Download our learning guides: PDF | Google Slide | Transcript Inside the husk is a tiny little droplet of water surrounded by something called the endosperm. The endosperm is what you're actually eating when you eat popcorn. When you heat up popcorn, the tiny droplet of water gets hot and turns into steam. That steam pushes through the endosperm and turns it kind of soft and that endosperm builds up pressure and explodes through the husk. When it explodes, that soft gelatinous endosperm hits cooler air and it hardens up in whatever shape it has exploded into. So that's why popcorn has all those funny shapes and feels kind of like foam. Salmon are born in freshwater, but then spend their lives in saltwater. They return to the freshwater to spawn (lay and fertilize eggs) and die. Some salmon return to any body of freshwater to spawn, but some salmon have special ways of finding their way back to the place they were born. They use a kind of internal compass to head back to the spot. Other fish rely on their sense of smell to find their way back to fresh water.  Animals that turn white in winter use the length of day as their cue to stop producing pigment in their fur. Their bodies can sense the hours of daylight, and when the daylight starts getting shorter, their hormones will tell the cells to stop producing melatonin.  Hormones tell the cells what to do to shut off the production of pigment in the fall and to turn it on again in the spring. It's not because the days and the nights get colder or warmer.  The fastest runner in the world is Usain Bolt. He's the fastest man who's ever been timed. He's a Jamaican sprinter, and he holds the world record for both the 100 and the 200 meter sprints. He has nine gold medals at the Olympics and 11 world championships. His record for the 100 meter sprint is 9.58 seconds. That is super fast. That's more than 23 miles an hour. Want to pop your own popcorn from kernels? Find a big pan with a tight-lid. Pour two tablespoons of cooking oil in the pan. Then add a half a cup of popping corn. Cover the pan and turn the heat to high. In a few minutes the popcorn will start to pop. Turn off the heat. Open the lid when the popcorn stops popping. Enjoy! How a zipper works Sounds Wild

Field trip time! Today we’re learning all about snakes while out on a search for timber rattlesnakes in New York with state wildlife biologist Lisa Pipino. Some of the questions we tackle: How do some snakes make venom? Why are some snakes venomous and others are not? Why do rattlesnakes have a rattle? How do snakes slither on the ground without legs? Why don’t snakes have legs? Why don’t snakes have ears? How do they smell with their tongues? Why do some snakes use heat vision? Do snakes sleep? Why do snakes stick out their tongues so much? Download our learning guides: PDF | Google Slide | Transcript Snakes are ectothermic - meaning they are cold-blooded and rely on their environment to regulate their body temperature. Snakes like to bask on warm rocks to stay warm. A rattlesnake’s first rattle segment is called a button. They shed their skin once or twice per year and each time they do, they get a new rattle segment. Rattle segments sit on top of each other, and when rattlesnakes shake their tail, the segments rattle. This noise is a warning to predators to stay away. Some snakes lay eggs. Others develop eggs that grow and hatch inside their body, meaning the snakes give birth to live young. Rattlesnakes give birth to live young but only stay with their babies for about a week. Those babies follow their mother’s scent trail back to the den for winter. Some snakes are venomous, but not poisonous. What’s the difference?! Venom is delivered through a bite or a stinger, while poison is usually inhaled, swallowed, or absorbed through the skin. Snake venom is a lot like saliva, except it’s toxic. Snakes create it using a special gland. They then use their venom to immobilize or kill their prey before they eat it. They sometimes use their venomous bite as a defense as well. Snakes do have nostrils and can smell through their nose a little bit. But they mostly use their tongues to smell and sense their environment. They stick out their tongues to pick up scents. And then they rub their tongues on a special organ at the top of their mouths, which sends a message about the scent to their brains. Timber rattlesnakes live in the Eastern US and are different from some of the other well-known rattlesnakes in the Western US. In much of the northeastern states they’re considered threatened or endangered. People shouldn’t try to look for these snakes because of the possibility of disturbing the snakes or their habitats.

Why do we feel pain when we get hurt? What is pain? Why do we cry when we get hurt? Why do we say ow or ouch? We’re learning about how pain works with Joshua Pate. He’s a physical therapist and author of a forthcoming children’s book series about pain. Download our learning guides: PDF | Google Slide | Transcript Pain happens when your body sends signals to your brain that something is wrong. And your brain sends signals to your body to feel pain! Pain is protective–it lets us know to stop doing something that is damaging or might damage our bodies. And it lets us know that something is wrong and we might need to get help from an adult or a medical provider. When you get hurt, like scraping your knee for example, the nerve cells in the knee send a message to the brain. Your eyes might see the scraped knee and send another message to your brain. Then your brain has to decide how much danger your knee is in. Pain is messaging that lets your brain know that something is not well. If you didn’t have that pain, you might keep scraping your knee over and over. Pain is biopsychosocial, meaning biology, psychology and social or environmental factors all play a role in what pain feels like for individual people. A lot of things can turn the feeling of pain up or down. Distraction, like listening to music or watching a video can help turn pain down. Staring at the source of pain can make it hurt more. Outside factors can also impact pain. In a study from several years ago, people were asked to hold a freezing cold rod. Scientists changed the colored lights in the room. When the lights were blue people felt less pain from the rod than when the lights were red. Normally, pain will recede when an injury heals. But not for everyone. Sometimes people suffer from chronic pain after an injury. We cry when we’re in pain as a way of letting others know that something is wrong. We also learn to use the words ow or ouch. Other languages have different words for pain.

Why do friends care about each other? How do you make friends? Can you have more than one best friend? How do you deal with a bully? We answer questions about friends and bullies with Dr. Friendtastic (also known as Eileen Kennedy-Moore), a psychologist and author of Growing Friendships: A Kids’ Guide to Making and Keeping Friends. And we get lots of advice from kids themselves about how to make friends and deal with bullies.  Download our learning guides: PDF | Google Slide | Transcript 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. 

How are crickets so loud? Why do they chirp at night? How are they different from grasshoppers? We’re talking crickets today with Karim Vahed, a cricket and katydid expert and entomologist (bug scientist) at the University of Derby in the United Kingdom. Professor Vahed also takes on some of your pressing insect questions: Do insects have bones? What do baby bugs like to do? Do insects drink water? Why are bugs so important? Download our learning guides: PDF | Google Slide | Transcript  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!

That’s just one of the questions we answer in this week’s episode, which also includes instructions on how to easily make your own ice cream at home! We’ll also tackle the why and how of melting ice cream and why some flavors tend to melt faster than others! Our expert in this episode is ice cream entrepreneur Rabia Kamara, of Ruby Scoops in Richmond, Virginia. It's going to be sweet! Download our learning guides: PDF | Google Slide  | Transcript After listening, if you're ready to try making ice cream at home, here's Rabia's easy recipe. INGREDIENTS: 2 cups of heavy cream 1 14oz can of sweetened condensed milk Optional additional flavorings: a splash of vanilla pinch of salt And whatever else you might want to add! (Chocolate chips, cookie crumbles, etc.) INSTRUCTIONS: Use a hand mixer to beat the heavy cream until it is the consistency of whipped cream, with peaks that hold their shape. Fold any additional ingredients into the sweetened condensed milk and add the mixture to the heavy cream and fold them together using a spoon. Put into a freezer safe container. Let freeze for about 8 hours. Enjoy!

The Washington Mystics of the WNBA join us in this episode to answer all of your questions about the sport of basketball and what it’s like to be a professional athlete. How many basketballs does the team have? Why do balls spin when you bounce them? Who invented basketball? Why are basketballs orange with black lines? Why do men and women play on separate teams? How do injuries impact professional careers? And do you have to be tall to play hoops? Download our learning guides: PDF | Google Slide | Transcript Resources Basketball Games for Kids Learn More About the WNBA

For the past 50 years, visitors to the Smithsonian National Zoo in Washington, D.C. have been able to observe giant pandas. It’s one of the few places in the United States to see these black and white bears. For our latest episode we took a field trip to the zoo to visit the three pandas currently living there and answer panda questions with zookeeper Mariel Lally. We tackle: Why do animals live in the zoo? Why are pandas black and white? Do pandas hibernate? How can we save the pandas? And check out our social media pages for lots of pictures! Download our learning guides: PDF | Google Slide | Transcript 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.  Resources National Zoo’s Panadriffic Pack (games and coloring pages) Panda Cam

What is climate change? What is causing climate change? How do you cool down the earth? How is climate change affecting the oceans? Kids are hearing about climate change and they have lots of questions. In this episode we explain the science of climate change and look at how humans will adapt to a rapidly warming planet. We speak with Dr. Claudia Benitez-Nelson, oceanographer at the University of South Carolina and Dr. Jola Ajibade, a geographer at Portland State University. This certainly isn’t a comprehensive look at the issue, but it’s a good way to start a conversation about this issue for families and teachers. Download our learning guides: PDF | Google Slide | Transcript 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. Resources NASA’s Climate Kids NASA’s Kids’ Guide to Climate Change National Geographic Kids Climate Change Explainer Take Action: Young Voices for the Planet Science Moms

Why do flowers bloom? How do flowers grow? Why are flowers different colors? Why do people find flowers beautiful? How are seeds made? Why do plants grow from seeds? Why do we put seeds in the garden? We’re answering your questions about seeds and flowers with garden writer Charlie Nardozzi and Hannes Dempewolf from The Crop Trust. Find more answers to plant questions in two of our older episodes: How Do Big Plants Grow From Such Small Seeds? and Are Seeds Alive?  Download our learning guides: PDF | Google Slide | Transcript 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.  Resources Seed sprouting experiment Window gardening for kids Webinar: Gardening with Kids