Why do lizards have scales? Why are reptiles cold-blooded? Why do lizards have long tongues? How do lizards grow their tails back? Are crocodiles dinosaurs? What?s the difference between an alligator and a crocodile? Why do crocodile eyes look like they have mirrors in the back? How do crocodiles chomp? Why do crocodile teeth stay sharp? Why are crocodiles green? Why do crocodiles swim? Answers to all of your crocodile and alligator questions with Venetia Briggs-Gonzalez, one of the researchers known as the Croc Docs at the University of Florida.

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Why do people dance? Where did ballet come from? How do you make pointe shoes for ballet? How does practice make you better at things? But Why visited Dance Theatre of Harlem to get answers to these questions with company artists Derek Brockington and Lindsey Donnell.

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A solar eclipse is coming to North America on April 8, 2024. The moon will line up perfectly between the Earth and the sun, blocking out the sun?s light and casting a shadow that will pass over parts of Mexico, the United States and Canada. People in the path of totality will experience a few minutes of darkness during the day as the moon perfectly covers the sun. Those not in the path of totality in those countries will still experience a partial solar eclipse. In this episode, we?re answering questions about the eclipse and talking about how to keep your eyes safe if you?re watching it! We speak with Bridgewater State University solar physicist Martina Arndt, Fairbanks Museum planetarium director Mark Breen and Thomas A. Hockey, author of America?s First Eclipse Chasers.

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Why are there Burmese pythons and chameleons in the Florida Everglades? We might not know how those animals arrived but they are causing damage to the natural ecosystem. An invasive species out competes native plants and animals in an ecosystem. So how does this happen? But Why travels to the Everglades to learn more about how and why species end up in places they shouldn?t. Plus, why are we sometimes told to kill invasive insects like the spotted lanternfly?

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How is snow made and what?s it made out of?  Why is it white and sparkly?  Why do snowflakes look different? Can snowstorms have thunder? Why do some places, like mountains, get more snow than others? Answers to all of your questions about snow, with Seth Linden, who works for the National Center for Atmospheric Research in Boulder, Colorado. Plus we hear what it?s like to live at the top of Mount Washington, famous for its extreme weather, from Alexandra Branton, a meteorologist who works at the observatory at the top of the mountain, even during the frigid winter.

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How do glasses work? Why do some people need glasses and other people don?t? Why do we have different eye colors? We answer your questions about glasses and eyes in the second of two episodes with Dr. Sujata Singh, a pediatric ophthalmologist at the University of Vermont Medical Center. And we hear from Maggie, a kid with low vision, about what it?s like to need glasses. 

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What shape are our eyes? What are they made of? How do they work? What?s the point of having two eyes if we only see one image? Why do we blink? What?s the point of tears and why are they salty? We answer your questions about eyes in the first of two episodes with Dr. Sujata Singh, a pediatric ophthalmologist at the University of Vermont Medical Center.

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We?ve collaborated with our podcast friends at What If World to bring you the first (and only) episode of?But Why If World! In this episode we jointly answer some ?what if? questions. What if cereal could talk to us? What if dinosaurs didn?t lay eggs? What if the world started spinning backwards? Take a listen to this curious collaboration.

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For our last episode of each year, we often like to ask our listeners around the world to send us something fun. This year, we wanted you to tell us what makes you happy and you had a lot to share on that topic! Our listeners find happiness in spending time with friends, family, and pets and in doing activities they love: playing with friends, toys, arts and crafts, participating in sports, watching movies, and riding bikes. Two people say the special sandwiches their adults make them are what bring them happiness. And some kids told us learning new skills is especially exciting for them. In this episode: a happiness bonanza with all the responses we got. Plus we talk with a happiness expert: Gretchen Rubin. She?s the author of the Happiness Project and host of a podcast called Happier with Gretchen Rubin. 

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Almost half the people in the world speak at least two languages. And, it turns out, that includes a lot of But Why listeners! In this episode we talk about what it?s like to speak multiple languages and kids from around the world share phrases in many different languages so we can all learn something new! Plus, linguist and professor Anna Babel answers questions we?ve gotten about languages, including: What does it mean to be bilingual? Why do some people speak two or three languages? How many languages can someone learn?

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How are electric guitars made? How are guitar strings made? And how, exactly, do guitars work? We?re answering questions about electric guitars with local luthier (guitarmaker) Lea in Burlington, Vermont. Creston gave us a tour of his studio?including his custom glitter room, to help us understand what goes into making an electric guitar.

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For the past 50 years, visitors to the Smithsonian National Zoo in Washington, D.C. were able to see giant pandas. But recently, China asked for those pandas back. (Technically, all pandas in the United States are considered ?on loan? from China.) With pandas in the news, we?re bringing back the episode from our 2022 field trip to the zoo. Zookeeper Mariel Lally answered all of your panda questions. Among the questions we tackled: Why do animals live in the zoo? Why are pandas black and white? Do pandas hibernate? How can we save the pandas? Check out our social media pages for lots of pictures!

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Why do we celebrate birthdays? Why do we have birthday cakes? Why do we blow out candles on our birthdays? Why are our birthdays on the same date but a different day of the week each year? This episode has answers to all of your birthday questions - plus we hear about unique birthday traditions sent in by our listeners! 

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Why do some people like haunted houses and scary movies? What is fear? Why do humans have fear! Why do we get goosebumps, blink a lot and scream when we?re scared? Why are some of us afraid of what?s in our closet or under the bed at night?

We look at fear, and the fun side of fear with Marc Andersen, who co-directs the Recreational Fear Lab at Aarhus University in Denmark. He studied fear and play and how they intersect. Turns out, moderate and controlled fear can actually have benefits to our mental health!

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How is meat made in a lab? That?s what 10-year-old Nate in New Jersey wants to know! Scientists have figured out how to grow meat in laboratories. Some hope lab-grown meat will be able to help address issues like global food insecurity, agricultural pollution and animal cruelty. But 5-year-old Lorenzo in California wants to know why people have to eat meat anyway? But Why visits scientist Rachael Floreani of the Engineered Biomaterials Research Laboratory at the University of Vermont to learn more about how and why lab-grown meat is being developed.

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Younger people have lots of questions about older people, like: Why do we age? Why do people get gray or white hair? Why do older people have wrinkles? Why do older people have veins that stick up? Why are older people more tired? Why do some people get shorter as they get older? Dr. Suvi Neukam, a geriatrician at Oregon Health and Sciences University, answers kids? questions about aging in this episode.

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Why do birds fly? How do raptors soar? Why do some birds fly in the shape of a V? Why can?t some birds, like penguins, emus and ostriches fly? Why do hummingbirds fly so fast? We answer all of your questions about birds and flight with help from Anna Morris of the Vermont Institute of Natural Science and Bridget Butler, the Bird Diva. And we get a preview of our new education series But Why: Adventures! Northeast Nature. Educators: learn more about But Why: Adventures! Northeast Nature and sign up for free access to the series!

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We?re thinking about bears! Actually one specific type of bear: sun bears! Have you heard about this type of bear? They?re the smallest of the world?s bears, about half the size of a black bear. They live throughout southeast Asia and have a yellow or white crescent-shaped marking on their chests. We learn about sun bears with Wong Siew Te, a scientist and researcher who runs the Bornean Sun Bear Conservation Centre in Malaysia. Also in this episode: Do bears live in caves? Why do they climb trees? Why do bears hibernate in winter? Naturalist Mary Holland answers questions about hibernation. And we are treated to A Bear Song by Key Wilde and Mr. Clarke!

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It's all about bikes in this episode of But Why? How come bicycles stay up when you're riding, but fall over once you stop? We turn to Andy Ruina, professor of engineering at Cornell University, for the scientific answer. We also learn how a bike chain works and Olympic mountain biker Lea Davison tells how to get started when riding.

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11-year-old Alaska (from Colorado) wants to know: why do some kids love reading while others don?t? We know there?s a lot of debate lately about the best ways to teach kids how to read. But in this episode we leave the pedagogy to adults and let kids share with one another why they love to read and their best tips for kids like them, who may be struggling to learn (and love) to read. Plus, guest Fumiko Hoeft, medical doctor and professor at the University of Connecticut and at the University of California San Francisco, lifts the lid on our brains to explain what?s happening inside us when we learn to read. Dr. Hoeft runs a brain imaging research program and a lab called BrainLENS.

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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) in England who works with BugLife, the Invertebrate Conservation Trust. In this episode, Professor Vahed takes on some of pressing general insect questions as well: Do insects have bones? What do baby bugs like to do? Do insects drink water? Why are bugs so important?

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Why is it that some people have allergies when others don?t, even if they?re in the same family? How do allergies work? Can you be allergic to water? Why are some people allergic to cats and dogs? Can you grow out of your allergies? We?re joined by pediatrician and allergy researcher Dr. Ruchi Gupta to answer the dozens of questions kids have sent us on this topic. Plus we learn about promising treatments being developed to help relieve allergy suffering.

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What are eels? And why are some eels electric? We head to Poughkeepsie, New York to learn about eels with Chris Bowser, Hudson River estuary educator with the New York Department of Environmental Conservation. Plus we learn about electric eels. Electric eels have captured the imagination of many people, but they?re not actually considered eels by the scientific community. They?re a type of knife fish, more closely related to catfish and carp. But they are electric! So we?ll tackle why they?re electric and how they create electricity. David de Santana, of the Smithsonian Museum of Natural History, tells us what it?s like to study electric eels in the Amazon. 

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Why do people spend so much time on social media? But Why answers kids' questions about social media and screen time and we learn about how to be a good citizen online with Devorah Heitner, author of Screenwise: Helping Kids Thrive (and Survive) in Their Digital World and Growing Up In Public: Coming of Age in a Digital World, coming in September.

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Why do wolves howl at the moon? Do wolves have different howls? How were wolves domesticated into dogs? How do wolves run fast for so long? What kind of habitats do wolves prefer? Why are people scared of wolves? Do they eat people? How do we protect them? But Why visits the Wolf Conservation Center in South Salem, New York, where education director Regan Downey answers kid questions about these apex predators.

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Do bears ever live in cities? Why do so many crows gather together on winter nights? How many raccoons are there in cities? What?s the deal with so many maple trees in Vermont? Why are flowers different colors? How are snakes born with venom? Why do some foxes turn white in the winter and others don?t? Where is a good place to observe wildlife? How do urban wild places support wildlife in cities? Naturalist Teage O?Connor answers questions from Burlington classrooms in this special live episode of But Why. 

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Why are babies small and grownups big? Why are babies so helpless, instead of little versions of adults? Do babies know they're babies? How do babies grow? How do babies learn to talk?

Kids have been sending us lots of questions about babies! This week we're learning more about the development of the human brain with Celeste Kidd, professor of psychology and primary investigator at the Kidd Lab at the University of California Berkeley.

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One of the things that makes blood so special is we can share it with other people! Scientists and doctors have figured out safe ways to take the blood from one person and put it into the body of a different person who needs it. That?s called a transfusion. Why would someone need more blood? Doctors use blood transfusions to help people who have been in accidents and to treat people with certain kinds of cancer, sickle cell disease and other conditions. But if you?ve never heard about this before, it can sound kind of strange and alarming to think about giving away something that is so necessary to your life! In our second blood-related episode we?ll tag along with Jane as she donates some of her own blood.

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Why do people have blood, what is it, and what does it do? How do our bodies make new blood? Is it red or blue? Why does blood taste like metal? And why do we have different blood types? Our listeners have a lot of questions about blood. We learn about blood with UVM Medical Center and Larner College of Medicine pathologist Dr. Sarah Harm. 

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How do water slides work and how are they built? Why do you have to be a certain age or height to go down a water slide? Where does the water in water parks come from? And which is easier to design and build: a water slide or a roller coaster? First we did a little research of our own at Jay Peak Pump House Water Park. (And by ?research? we mean ?going down the water slides.?) And to teach us more about what?s actually happening when you take your thrill ride, we talked with water slide engineers Songyi Moon and Kelly Sall at WhiteWater West.

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In this episode: part two of parentisms- you know, the things adults like to say that may or may not be true. So many of these sayings have to do with food: Eating carrots will improve your vision.  Drinking coffee will make you shorter. Don?t swallow watermelon seeds or they?ll grow in your stomach. We do a little fact checking on this generational eating advice with Dr. Nusheen Ameenuddin of the Mayo Clinic. And we explore a few other sayings you sent us, like why do parents always say, ?Next time? when they really mean ?No?? And what the heck does it mean to keep your eyes peeled?

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We wanted to hear about the conventional wisdom, parenting myths, and downright folksy falsehoods adults pass down to kids, and boy did we get a big response! We heard from over 100 of you about everything from ?Don?t swallow gum because it will stay in your stomach forever? to ?Slouching will crush your organs? to ?If you don?t take a shower after swimming in the pool, your hair will turn green.? In this episode (the first of two), with the help of pediatrician Nusheen Ameenuddin of the Mayo Clinic, we put these ?parentisms? to the test! Find out if there?s any truth to the idea that TV will turn your brain to mush, you?ll catch a cold if you go out with wet hair, and it?s dangerous to take a shower during a thunderstorm. Oh, and by the way, this is our 200th episode!!!

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In addition to having faces that look like a smiley emoticon, axolotls are as fascinating to scientific researchers as they are to kids because of their amazing ability to regenerate parts of their bodies, including their brains! In this episode we answer kids' questions about these curious salamanders with Dr. Randal Voss, a professor at the University of Kentucky. That lab alone has thousands of axolotls, but these creatures are critically endangered in the wild, where they live exclusively in the depleted and polluted waterways of Mexico City?s Lake Xochimilco. Questions we tackle in this episode: How do axolotls regrow parts of their brains? What did axolotls evolve from? Can axolotls survive out of water?

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What do bison, moose, Gila monsters, parrots and snails have in common? Well?.nothing, except they all appear in this episode! We?re rounding up some of the animal questions you?ve sent us lately. Why do bison walk slow but run fast? What?s the thing hanging down from the neck of a moose? Why do Gila monsters bite? How do parrots talk? Why do snails have slime? Answers from the Fort Worth Nature Center & Refuge, San Diego Zoo Wildlife Alliance and One Earth Conservation.

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As we close out 2022, Jane and Melody look back at some of their favorite episodes of 2002. Why do we have friends? Why are some people left-handed? Why do pigs oink? And why is Russia invading Ukraine? Did you have a favorite episode? Let us know! Kids can record a video talking about a favorite episode and then tag us on social media or send an email to [email protected].

Episode Transcript

Full episodes

Why do we have friends?

Why are some people left-handed?

Why do pigs oink?

Why is Russia invading Ukraine? 

How do big cargo ships and ferries float, even though they are so heavy? Why do boats float but stones sink? How do paddles make boats move? What?s inside those enormous container ships? We learn about the physics of floating with Fahad Mahmood, professor of physics at the University of Illinois Urbana-Champaign. If you do any of the activities we mention in the episode, send us your videos!

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Why do armadillos have shells? How do they roll into balls? Why are sloths so slow? Can sloths actually move fast? How do they defend against predators? Why do they have such long nails? We learn about two unique looking animals in this episode: sloths and armadillos. These mammals are part of an ancient superorder called Xenarthra and share a common ancestor. To get answers to kid questions about armadillos we took a field trip to Texas to talk with Michael Perez at the Forth Worth Nature Center and Refuge. And to learn about sloths, we interviewed Sam Trull of the Sloth Institute in Costa Rica.

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Emoji are those little images you can send in text messages to friends and family. Nine-year-old Leila in New Jersey wants to know how they were invented. So in this episode we find out with Jane Solomon, editor at Emojipedia and Paul Galloway of the Museum of Modern Art in New York. We learn what the first emoji looked like, way back in the dark ages of the 1990s and we explore how emoji may be a new trend, but communicating through pictures is a very old tradition. Plus, are emoji?art? Give this episode a ?to find out!

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But Why has answers to your dinosaur questions! When did the dinosaurs live? How many species of dinosaurs were alive in the Cretaceous period? How do dinosaurs get their names (and why are they hard to say)? Why are dinosaurs extinct? We visit Dinosaur Valley State Park in Texas to see some actual dinosaur evidence: tracks left by two types of dinosaur 113 million years ago.

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Dinosaur Valley State Park in Glen Rose, Texas has several sites where dinosaur footprints have been well-preserved. Though some of the tracks were actually chiseled out and sold before the park got state recognition and protection.

In the summer of 2022, drought in this part of Texas caused riverbeds to dry out, revealing new tracks that hadn?t been seen before. These discoveries made news around the world!

The rock in the area is limestone. And the tracks are largely in what are now riverbeds. But In the time of the dinosaurs, 113 million years ago, the landscape looked very different. The sea covered much of the land, and the spots where the tracks are were the seashore, full of sticky wet mud. The dinosaurs walked through the mud and left footprints, which were then covered over by silt and other sediment. As the mud got compressed and eventually turned into limestone, the tracks were preserved.

The landscape changed over the millennia. As the sea receded and rivers curved through the landscape, the flowing water eroded the limestone, eventually revealing these tracks that had been covered for millions of years.

Some of the tracks at Dinosaur Valley State Park are about the size of a large dinner plate look like classic dinosaur prints, with three long toes and claw marks. Those are from a dinosaur called Acrocanthosaurus.

Acrocanthosaurus was shaped like a Tyrannosaurus Rex. It walked on two legs and had a large ridge down its back. It was a carnivore and likely the apex predator in its North American environment.

The other dinosaur whose tracks have been found at this state park is Sauroposeidon. These tracks are much bigger and rounder, more like an elephant track. They?re so big a kid could sit inside one as if it was a bathtub!

Sauroposeidon was a huge dinosaur. It walked on all fours and had a long tail and a very long neck. It weighed as much as 44 tons and was as tall as a 6-story building. In fact, it may have been the tallest animal that has ever lived!

Sauroposeidon was an herbivore, and may even have been hunted by Acrocanthosaurus. The two dinosaurs lived at the same time and made the visible tracks at the park within hours or days of each other.

The biggest dinosaurs lived in the Cretaceous period,145 million to 65 million years ago. It?s estimated there were as many as a thousand different dinosaur species in that time period, but only a few hundred have so far been named.

Most paleontologists believe most dinosaurs died out more than 65 million years ago when an asteroid hit planet Earth.The asteroid itself didn?t kill all the dinosaurs all at once, though it was big enough to cause a lot of devastation. It also kicked up a huge cloud of dust and debris that essentially blocked sunlight from reaching the earth. This caused plants to die. Without plants, large herbivores didn?t have enough to eat. When the herbivores died, the carnivores had nothing to eat and they died, too.

If you want to see the dinosaur tracks, check out our videos on YouTube.

Kids love cheese! (So do adults: Americans consume an average of 40 pounds of cheese per person per year.) In this episode we learn how cheese is made and answer all of your cheesy questions: Why are there different types of cheese? Why do cheeses have different flavors? How do you make Colby Jack cheese? How does cheese get its color? And why do we say cheese when we take a picture? We visit the Cabot Cheese factory and talk with Maegen Olsen and Panos Lekkas.

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Cheese starts with milk. Cheese is often made with milk from cows or goats, but it can also be made with milk from sheep, buffalo, camels or other mammals. (There?s even a moose-cheese company in Russia!) If the cheese is made in bulk to sell to lots of people, companies will usually run tests on the milk before they turn it into cheese. They want to make sure it doesn?t have bad bacteria or antibiotics in it. The milk is then pasteurized, which means it?s heated quickly and cooled quickly to kill any lurking bad bacteria.

Next cheesemakers will add a starter culture. Starter culture is GOOD bacteria, which will eat the milk sugar (lactose), create lactic acid and drive down the pH of the milk. That helps create curds.

The next step is coagulation! (Coagulation is the process of turning a liquid into a semi-solid or solid.) To coagulate the milk, an enzyme called rennet is added.

Now it?s time to separate the curds from the whey. Cheesemakers will use knives to cut the coagulated milk into chunks known as curds, leaving some liquid behind. That liquid is known as whey. When milk is made into cheddar it gives a 10% yield, meaning 10% of the milk will become cheese and 90% will be left over as whey. Some cheesemakers, like Cabot, use the whey to make protein powders. In other factories it might go to waste.

Next, it?s time to add salt. Salt serves as a preservative and gives the cheese flavor. If it?s a flavored cheese, things like garlic or peppers will be added at this point.

The cheese is then pressed into blocks. At factories like Cabot, they pull the curds into tall towers and then add more and more, creating pressure that forms those curds into solid blocks. Smaller cheesemakers use a cheese press.

In the final step, the cheese is aged. It will sit in a cold storage or cheese cave and just?get older. Cheddar can be aged for years, giving it a stronger flavor. Aging also changes the texture of a cheese like cheddar. It can get more crumbly the older it gets. Once it?s ready, it will be cut, packaged and shipped to stores.

Why do bees pollinate? How do they make honey? Why do bees have stingers? Why do (some) bees die when they sting you? What's the difference between a bee and a wasp? Does honey have healing properties? Farmer and beekeeper John Hayden answers all of your bee questions!

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Bees collect nectar from flowers. Nectar is the sweet liquid that entices the bees to the flower. The bees climb onto or into the flower and suck up the nectar with their straw-like mouth and collect it in a little sac called a crop. They also collect pollen on their legs. As they move from flower to flower, they leave a little bit of that pollen on each new flower they visit. That's called pollination and it?s how flowers reproduce.

Bees take the pollen and nectar back to their hives and put it into the honeycomb (six-sided cells they have built out with wax). Pollen is like protein, one of the building blocks of animal bodies, and bees use that to feed their young mostly.

To turn nectar into honey, bees spit it up into other bees? mouths and eventually they spit the liquid into the honeycomb cells. Then they fan it with their wings to evaporate some of the moisture. Once it has reached the right consistency, they seal it off with wax to store it for later. So honey is just concentrated nectar.

Bees keep the honey in storage for the winter months when there are no flowers. But they make more than they need, so beekeepers take the extra honey out of the hive and leave the bees enough to survive through the winter.

Bees sting to protect their hive and defend their honey from potential predators. But honeybees don?t sting unless they have to, because after they sting, their stinger gets pulled out of their body and they die! Honeybees die when they sting because their stinger has a barb on it, like a fish hook. The stinger gets hooked into your skin and then when the bee tries to fly away the hook stays in and pulls out the bee's abdomen as it flies away.

Honeybees are social insects who depend on their colony to survive. So they are willing to sacrifice themselves to make sure the whole colony can survive.

Honeybees are far from the only pollinator. Bees are very important to our ecosystem and there are more than 4000 species in the US alone. Butterflies, hummingbirds, and bats also play important pollinator roles.

Resources

How do big plants grow from small seeds?

How are babies made? 

Honeybee music video

Why do sharks have multiple sets of teeth? Why do sharks lose so many teeth? Do sharks eat fish? How do sharks breathe underwater? Do sharks sleep? Give a listen to this totally jaw-some conversation about sharks with Dr. Kady Lyons, shark researcher at the Georgia Aquarium! We also tackle: Why are dinosaurs extinct and sharks are not? Were megalodons the biggest sharks in the world? Do sharks have noses? How do sharks communicate? Why do sharks bite? Why are sharks dangerous?

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Sharks are a type of fish. They?ve been around for millions of years and their body plan hasn?t changed much in that time!

Sharks? skeletons are made of cartilage. They don?t have any calcified bones - so the only part of a shark that gets left behind in fossil records is their teeth! 

Megalodons were the biggest shark, but they are extinct (despite sensational TV shows that claim otherwise). The latest research suggests megalodons were bigger than modern day humpback whales!

Sharks and other fish breathe by extracting oxygen from water by the use of their gills. Gills are made of very thin tissue. The blood inside the tissue picks up oxygen from the water and brings it into the organs in the fish?s body. 

Sharks evolved to have sharp teeth to grab slippery fish and other prey. If they break a tooth, they can regrow a new one, and they just drop the old one. Easily replacing a tooth that breaks off is a strategy that allows them to keep hunting. Their teeth grow continually through a shark?s life, moving forward in their mouth kind of like on a conveyor belt, maturing as they go. So when a tooth falls out a new one moves forward. Some sharks lose whole rows of teeth, like dentures, all at the same time.

All sharks are carnivores, eating fish, seals, and sometimes other sharks. Some species, like whale sharks, filter feed, mostly on zooplankton but sometimes phytoplankton (sea plants) as well.

Sharks have been known to attack humans, but humans actually aren?t great prey for them because we lack a thick layer of blubber or other energy the sharks are on the hunt for. Usually sharks attack when they mistake a human for something else, like a seal. 

Sharks go through periods of sleep or rest, reducing brain activity. 

Sharks have a fantastic sense of smell. It helps them find their prey. 

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!

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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?

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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.

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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. 

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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?

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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 w?t? [say it: WEH-tah] is that insect!  There are several species of giant w?t?s. 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?

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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