How are rocks made? Why are some rocks hard and others soft? How do rocks shine? How are geodes and crystals made? Why do some rocks have gems in them? Answers to your rock questions with Hendratta Ali, rock doctor! Ali is a geologist who studies and teaches at Fort Hays State University in Kansas. Download our learning guides: PDF | Google Slide | Transcript

Is it OK to do something that you were told not to do and then never tell anybody? In this episode we tackle that thorny question from 10-year-old Finn from Seattle. We'll also wrestle with the question, "Why do people make really bad choices and want other people's lives to be harder?" Download our learning guides: PDF | Google Slide | Transcript We're tackling some ethical dilemmas in this episode and we're letting kids give the answers! We also get a response from ABC Radio's Short & Curly, a podcast devoted to ethics for kids. Here's how some of our young listeners answer the question about whether it's ever okay to break a rule and lying about it: "No, because it usually just means you get in trouble." - Juniper "I think so. If you're protecting somebody or keeping a surprise." - Camille "It depends who told you. Like if your parents told you, then you shouldn't do it. Or if you do it, you should tell them you did it. But if it's like a mean person you met on the street it's ok. And it depends what it is. Because if it's a bad question, you shouldn't do it either way if it's a bad thing. If it's a good deed you should do it. And if you did that, why wouldn't you tell anyone?" -Sylvie "No, not really. If you don't tell anyone about it. It's mostly the doing it and then not telling anybody about it. Mostly what isn't the good thing about it. It's a little bit worse, if you don't tell someone you might get a feeling where you feel kind of embarrassed. And you don't tell anybody and it just sticks with you the rest of your life."  - Piper

Have you ever felt competitive with a friend or a sibling? Competition comes up in a lot of different ways in life. Maybe you're running a race with a friend and you want to beat them! Maybe you're trying to play a song without making a mistake and you're competing against yourself. Sometimes competition feels good and fun. It can make you want to do better, and make a game more enjoyable. But not always. Sometimes competition feels bad. Like it's too much pressure, or takes away from the fun of being with your friends. Some people really don't like competition at all. 3-year-old Kai from Tokyo, Japan asks: "Why do we need to compete with other people, especially friends, for example on a sports day or at gym class?" In this episode we discuss competition with anthropologist Niko Besnier. And we'll hear from 12-year-old Harini Logan, a competitive speller from San Antonio, Texas, and 10-year-old Del Guilmette, an athlete from Monkton, Vermont. Download our learning guides: PDF | Google Slide | Transcript We put Kai's question to Niko Besnier, anthropologist at the University of Amsterdam.  One of his books is called The Anthropology of Sport, written with Susan Brownell and Thomas F. Carter. He says there are two reasons that people take part in competitions: "One is that sports are fun. It's fun to play with your friends and classmates, to run, jump, play ball. We've all experienced this rush of pleasure and fun doing these things. But the other aspect that's contradictory to the fun part is that it enables us to measure our strength, our speed, our physical ability against those of other people. It's the competition part of sport, and competition can become extremely serious. Frequently, the fun part of sport gets lost." Besnier says when competition gets out of hand it can lead to hurt feelings, and on a larger scale, competition can lead to things like war and inequality. But with the right attitude, competition, especially when we compete against ourselves, can help us get better at sports and academics. That's how it is for Harini Logan. She's a competitive speller who has made it to the Scripps National Spelling Bee twice! "Competition teaches you a lot, whether it's the preparation leading up to that competition or the outcome," Logan says. "It can teach you a lot about not only your abilities, but also new things that can change the way you look at life. When you're preparing for a competition you can learn how to work hard, and how not to give up on something. And during the competition you learn teamwork. That's one thing you learn in spelling bees, because you want to be with your community, your friends. One thing to learn if you win: sportsmanship! You don't gloat about it, you still appreciate yourself but you don't overdo it so others don't feel bad. And if you don't win it doesn't matter. [You just say:] I'm going to try harder next time." Competing also helps us get better. That's how 10-year-old Del Guilmette views it. He likes to play against tough teams when he plays sports, because that's how you get better. "The best players at the game, whatever sport it is, they didn't get better because they played teams that they knew they were going to beat. They played those teams that were better than them. They got better and they practiced!" Listen to the full episode to hear more about how these mature young competitors think about the value of competition.

In the ice age, megafauna roamed North America: mammoths, saber-toothed cats, even giant land sloths! What happened to them? In this episode we answer questions about the ice age: What was it? Did birds live during that time period? How about giraffes? Did people live with woolly mammoths? Why did mammoths go extinct? We'll answer your questions with Ross MacPhee, senior curator at the American Museum of Natural History and author of End of Megafauna: The Fate of the World's Hugest, Fiercest, and Strangest Animals. And we'll hear from Nathaniel Kitchel, a Dartmouth researcher who used carbon dating to discover the age of a mammoth rib. Plus, John Moody, of the Winter Center for Indigenous Traditions in Norwich, Vermont, on how mammoths appear in the oral history of the Abenaki people. Download our learning guides: PDF | Google Slide | Transcript "What was the ice age?" -Karen, 5, Wilmington, Delaware In the Pleistocene era, which lasted from 120,000 years ago to 15,000 years ago, ice covered the landscape in much of the northern hemisphere. Ice covered all of Canada down into the Northern United States and all of northern Europe. And there were smaller ice sheets in Russia. How did this happen? Scientists think it was a buildup of ice over time. "The theory is that the winter never ended," explained Ross MacPhee. "You would have snowfalls in the winter and it never really got warm enough to get rid of it completely. The next year that would be built on, built on and built on. And the thing about snow is that it kind of makes its own weather. If you have snow it gets very cold! And that preserves the snow pack for a very long time." The weight of that snow would compact into ice, eventually covering parts of the world in great sheets of ice. It might help to think of the process as a little bit like what happens when you have a favorite sledding hill: the snow is light and fluffy when you start, but if you sled down it enough times (and walk up the hill, too), eventually the paths get icy from the footsteps and sleds continually packing the snow down. It wasn't just ice sheets that were a feature of the ice age. All of that water caught up in the ice made sea level drop 300 feet lower than it is now. That exposed lots of land that is now covered in water, including a land bridge connecting Alaska and Russia! This land bridge allowed a number of species to move into North America from Asia, like bison. And some North American animals went into Asia, like camels and horses! Bear species traveled in both directions. Humans also used the land bridge to migrate into North America, though scientists think some early humans probably used boats too. Mammoths also migrated over that land bridge! They originated in Asia and came into North America. But there were other species of megafauna that roam the landscape as well, like giant condors, saber toothed cats and even giant sloths. These species went extinct at the same time as mammoths, as the ice age was ending. Listen to the episode to learn more about the theories of why so many large animals went extinct around the same time.

In 2019, we answered a question about the Great Pacific Garbage Patch, a huge mass of plastic and other trash swirling around in the Pacific Ocean. Mary James heard that episode and was so inspired, she created a device to help clean up the plastic in the ocean. In this episode of But Why, we learn about her invention, the mermicorn! Download our learning guides: PDF | Google Slide | Transcript Listen back to Why Is There A Big Patch Of Garbage In the Pacific Ocean? Kids: we'd like to know what you think could be done about all the garbage in the ocean. Download our learning guide above to draw a picture or describe an invention you would make to help clean it all up. Mary James sent her picture of the mermicorn to the Little Inventors competition, for Canadian children. See Mary's entry here. Her invention has been chosen from among hundreds of other submissions to be turned into a prototype, a model of what the real thing might look like. There are Little Inventors competitions in the UK as well, and lots of countries and organizations sponsor design challenges for kids. See if you can find one where you live!

On Thursday, February 18th, a robot called a rover is expected to land on the surface of Mars, and begin collecting information scientists hope will help us learn if life ever existed on that planet! We answer your Mars questions with Mitch Schulte, NASA program scientist for the Mars 2020 mission. Download our learning guides: PDF | Google Slide | Transcript NASA has a number of ways that you can watch the landing live on February 18th at 11:15 a.m. PST / 2:15 p.m. EST / 19:15 UTC. The rover is called Perseverance, which means not giving up, continuing to work toward a difficult goal even when challenges are placed in your way. And it is quite a challenge just to get to Mars! The rover was launched on a rocket from Cape Canaveral in Florida more than 6 months ago, by NASA, the U.S. Space Agency. And it has been traveling through space ever since, on a path to Mars. And now, people all over the world are eager to watch it land on Mars and get to work. And it’s not just Perseverance that is going to land on Mars. There’s also a helicopter, called Ingenuity, which means cleverness, creativeness and resourcefulness all rolled into one. Ingenuity, the helicopter, is basically a drone—there’s no one inside driving it around, just as there are no people onboard the rover. But ingenuity is the first helicopter to ever test-fly on another planet!

How is chocolate made? Why can't we eat chocolate all the time? Why is chocolate dangerous for dogs? Why do adults like coffee? In this episode, we tour Taza Chocolate in Somerville, Massachusetts to learn how chocolate goes from bean to bar. Then we visit a coffee roaster in Maine to learn about this parent-fuel that so many kids find gross! And we'll learn a little about Valentine’s Day. Download our learning guides: PDF | Google Slides | Transcript "How is chocolate made?" - Samarah, 8, Johnson, VT "Chocolate actually comes from cocoa beans--which is no bean at all--they are seeds of the cacao trees," says Ayala Ben-Chaim of Taza Chocolate. Taza is a "bean-to-bar" chocolate maker. That means starting with raw cocoa beans and going all the way through the process to turn those beans into a chocolate bar you can buy in a store. (Some chocolatiers get chocolate that's already mostly made and they just add stuff to it and shape it.) The tree that those cocoa beans come from is called the Theobroma cacao tree, which grows in warm tropical parts of the world--within 20 degrees of the equator. Taza Chocolate sources (buys) cocoa beans from farmers in the Dominican Republic, Haiti, Belize and Bolivia. It takes about five years from when it's planted for a cacao tree to produce cocoa pods. "Cocoa pods are a little bit funny to look at. They look like a gourd growing off of the tree, or like a lumpy tiny American football. The cocoa pods grow off of the branches of the tree like apples, but they also grow right off of the trunk of the tree," Ben-Chaim explains. "The next step in the process is fermentation. Fermentation is so important in chocolate making. And this is one of the things that is so surprising about chocolate making. After the beans ferment, they spend a week drying in the sun on wooden planks. At this point they look like almonds. Next, they are packaged and shipped to wherever they'll be made into chocolate. The first thing the chocolate maker will do is roast the beans at 200 degrees for about an hour, which gives them a nice toasted flavor. "We also start to separate the thin outer shell that surrounds the inner part of the cocoa bean. Our next step is to separate that shell from the inner part of the bean, called the nib. We do this by winnowing the cocoa beans, using a machine," says Ben-Chaim. "At Taza Chocolates we use a traditional Mexican milling style using a molino - or mill - to grind the cocoa beans down," Ben-Chaim says, demonstrating. "Over time, those cocoa nibs will be turned into a cocoa liquor, which is smooth and chocolaty. Imagine a chocolate waterfall. It looks beautiful, it smells chocolaty and delicious and yet it is not very tasty because we're missing a really important ingredient, and that is sugar." Sugar is added to the chocolate liquor, then the sweetened chocolate is ground again, and other ingredients are sometimes added, like spices or coffee or fruit. At this point some chocolate makers will conche the chocolate, which blends and mixes the chocolate at a high temperature over many hours, which makes it smooth and creamy. Taza doesn’t conche their chocolate. The next step is tempering. Tempering the chocolate makes it glossy and brittle. Then the chocolate is poured into molds and cooled. Then it's wrapped up and ready to take home. Also in this episode:  we visit 44 North Coffee  to learn more about the mysterious beverage that so many adults like to drink--coffee!

What makes a cactus a cactus? And what are you supposed to call a group of these plants--cacti, cactuses, or cactus?! We'll find out in today's episode, as we learn more about the cactus family with Kimberlie McCue of the Desert Botanical Garden in Phoenix, Arizona. She'll answer kid questions about why cactuses are spiky and how they got those spikes, as well as why teddy bear cactuses aren't actually cuddly! Download our learning Guides: PDF | Google Slide | Transcript Those prickly spines that are so characteristic of the cactus family are actually modified leaves! Cactuses don't have the kind of leaves like a maple or oak tree. But they might have had leaves that were at least a little more like that way way back in the past. Over time, those leaves evolved into the spiky spines we see on cactuses today because they help the plants survive in hot, dry environments. Why are cactuses spiky? -Noah, Iowa "They can be a defense mechanism to discourage herbivores - animals that eat plants - from eating the cactus. But, also, spines create shade!" explains Kimberlie McCue. "When you're covered in spines, as the sun moves across the sky, those spines are casting shadows on the body of the cactus. They're little shade umbrellas!" All cactuses are native to desert environments, and some live in places where it never rains at all. So how do they get water to survive? Well, Kimberlie tells us that these plants grow not too far from the ocean. "Early in the morning, there will be fog that comes off the water. Those spines provide a place for the water to condense, form little droplets of water that run down the spine, to the body of the plant, down to the ground and to the roots." Cactuses are also extremely important parts of their desert environments, as they hold soil in place and provide shelter for birds and other animals. Those insects and birds in turn help pollinate the cactus flowers. Cactuses are also an important local food source for humans. Unfortunately, cactuses are in danger from people who poach (illegally take) wild plants from their environment. Kimberlie McCue says one way to help make sure cacti stay healthy and plentiful is to be careful when you buy cactus plants. Check to see where the plant seller got the cactus and make sure they're taking care to be ethical stewards of these plants before you buy.

Why are whale sharks called whale sharks? Why are guinea pigs called pigs if they're not pigs? Why are eagles called bald eagles if they're not bald? You also ask us lots of questions about why and how animals got their names. So today we're going to introduce you to the concept of taxonomy, or how animals are categorized, and we'll also talk about the difference between scientific and common names. We'll learn about the reasoning behind the names of daddy long legs, killer whales, fox snakes, German shepherds and more! Our guests are Steve and Matt Murrie, authors of The Screaming Hairy Armadillo, and 76 Other Animals With Weird Wild Names. Download our learning guides: PDF | Google Slide | Transcript There are some animals whose names don't really seem accurate-like daddy long legs...which certainly aren't all daddies! Or bald eagles that very clearly have plenty of feathers on their heads. Or guinea pigs, which aren't actually pigs! And then there are animals with awesomely silly names. Have you ever heard of the umbrella bird? How about the sparklemuffin peacock spider!  Or the monkeyface prickleback, the sarcastic fringehead, and the white-bellied go-away bird! How do animals get their names? Well, there are two types of animal names: Scientific names and common names. Scientific names are used as a way to categorize all living things, so even if you don't know a lot about an animal, you can learn a lot about them by knowing their scientific name. There are eight different levels that living things get grouped into: domain, kingdom, phylum, class, order, family, genus and species. The broadest category is called the domain. There are three domains: archaea, bacteria, and eucarya. Bacteria and archaea are both categories of micro-organisms. All animals and plants belong in the eucarya domain. Below domain is kingdom. There's a kingdom for animals called Animalia and a kingdom for plants called plantae. (And a few others as well.) As you go through the classification system it gets more and more specific. So, take humans: we belong to the eucarya domain, the animalia kingdom, the chordata phylum (because we have a backbone), the mammalia class (because we're mammals), the primate order, homonidae family, homo is our genus and homo sapien is our species name. All species have two official scientific names, kind of like how you have a first name and a family name. So the species name for humans is homo sapien. The species name for a common black rat is rattus rattus. An Asian elephant is elephas maximus. Those names sound fancy, and originally the scientific names of animals were in Latin or Greek, but they don't have to be Latin or Greek anymore, they just have to sound like they are! But we don't typically call all animals by their scientific names. We often refer to them by their common names, which are kind of like nicknames! Common names can be different in different languages. Like, the scientific name for a wolf is canus lupus. That would stay the same no matter what language you're using. But in English we tend to call it a wolf; in Spanish you'd call it un lobo, and in Welsh it would be blaidd (pronounced "blythe"). Even within the same language, an animal can have lots of common names. Here in Vermont, where I live, we have an animal called a groundhog. But most people around here call it a woodchuck. And others call it a land beaver, or a whistle pig! Common names were often in use long before animals go their specific scientific names.

As the new year dawns, what are you hopeful for in 2021? Even though the change of the calendar year is mostly symbolic, New Year's Day is often a time for looking back on the year that just passed and setting goals for the year ahead. We asked you to share your hopes and dreams for 2021, from the end of the COVID-19 pandemic to your own personal goals. In this episode, more than 100 kids from around the world offer New Year's resolutions. We'll also hear from Johns Hopkins University epidemiologist Jennifer Nuzzo, climate activist Bill McKibben and Young Peoples Poet Laureate Naomi Shihab Nye. Download our learning guides: PDF | Google Slide | Transcript Here are just a few of the hopes and dreams you sent us: "My environmental wish for 2021 is that we can stop so much pollution. My personal wish is to learn Urdu and to convince my brother to get a cat or dog!" - Maya, Toronto, Ontario "My wish for 2021 is that the coronavirus will stop and the vaccine will come out and we can do things we haven't done this year and we can have our birthday together this year!" -Zain "I want to learn how to ride my bike by myself. - Adelaide, 6, California "What I want to happen for the new year is that I want people to start being responsible and no coronavirus. I want people to stop polluting. I want people to wear more masks. I want people to be kind to animals." - Jedi, 8, Ohio "I hope in 2021 more people think about and believe in climate change." -Evelyn, Albany, New York "Next year I would like more electric cars!" - Kyrav, 6, Geneva, Switzerland "My hope for next year is that we don't use as much plastic as we do now and that coronavirus will stop so we're able to do the things we like to do." - Tejas, Canberra, Australia "My hope for 2021 is that everyone gets health care." - Mikal, 7, Georgia My new year’s resolution is for sloths to take over the world and for people to use less plastic. - Sloan, 7, Wisconsin