Blood tests are pretty common. A phlebotomist -- which is a really cool word for someone whose job is it to take blood samples -- can either take a small amount of blood by pricking your fingertip, or they may go to a vein in your arm for bigger samples.

But why blood? Why not spit? Or pee? Or even a nice deep exhale?

In this episode, we'll find out the super important role blood plays in your body and why that means it has so many clues about what's going on in there. We'll get a traffic report about the busy blood superhighway, and visit a lab to see how it's tested. Plus, we'll hear about scientists efforts to invent a kind of synthetic blood. And as always, a brand new mystery sound!

Audio Transcript

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ZOE: You're listening to Brains On, where we're serious about being curious.

NARRATOR: Brains On is supported, in part, by a grant from the National Science Foundation.

LEROY LEECH: OK, just get hold of yourself. You can do this. You just have to get up this walkway. Let's just check to make sure I'm looking my best, OK? Black, slimy, skin, yep, yep, OK. Lovely, sharp, teeth, OK. Not bad. Not bad. You look like a leech who's about to land a new job. Let's do this.

INTERVIEWER: Can I help you?

LEROY LEECH: Oh, yes, hello. I'm here for the job interview. I saw in the paper you're looking to hire a nurse. I sent over my application yesterday.

INTERVIEWER: Oh, of course. Mr. Leech?

LEROY LEECH: Mm-hmm, mm-hmm, yep, Leroy Leech.

INTERVIEWER: OK, Mr. Leech, you can take a seat right over there right between the vampire and the mosquito.


MOSQUITO: Ugh, another one. What's a mosquito got to do to get a job around here? You're all wasting your time. We all know I'd make the best nurse.


VAMPIRE: And what makes you say that? A nurse takes blood samples and let's just say, I am an expert at that.

MOSQUITO: Exactly my point. I literally live to take blood samples.

VAMPIRE: Yes, those teeny-tiny sips of blood you mosquitoes take through skinny, little straws. So adorable. Well, I'm sure all your preparation won't be, should I say this, in vain.


MOSQUITO: Oh, have you know that whenever I enter a room, everyone starts clapping and waving their arms around? That's how excited they are to see me.

INTERVIEWER: OK, Mr. Leech, we're ready for you now. Tell us, why do you think you'd make a good nurse?


LEROY LEECH: Well, I'm used to working very long days. I always latch on to whatever task is in front of me. And I'm an expert at taking blood samples.

INTERVIEWER: Your resume is impressive. Top of your class at University of Leechburg, 10 years of experience in parasite satisfaction management, expert in shallow, stagnant ponds. Well, I can't believe I'm saying this, Mr. Leech, but you're hired.

LEROY LEECH: Sure, sure, sure, sure, sure. How about we shake on it. Just hold out your arm.


That's right. Now roll up your sleeve. Higher.


MOLLY BLOOM: You're listening to Brains On from APM Studios. I'm Molly Bloom, and with me today is Zoe from Las Piedras, Puerto Rico. Hi, Zoe.

ZOE: Hey, Molly.

MOLLY BLOOM: So today we're talking all about blood. And as always, the inspiration for this episode came from one of our listeners.

ELLIS: My name is Ellis, and I'm from New Orleans. My question is how do they do blood tests? How do they know what's in there?

MOLLY BLOOM: That's a great question. So Zoe, I'm wondering, have you ever had to have your blood tested before?

ZOE: Yes, I don't really like it, but.

MOLLY BLOOM: Yeah, so they've had to take blood from your arm?

ZOE: Yeah, I don't like needles.

MOLLY BLOOM: Yeah, I look away. I've had lots of blood tests in my life, and I look away from the needle. That's sort of my trick is, "I'm just going to pretend it's not happening." And then it's over before I know it. After they've taken your blood, have you kind of looked to see what it looks in the tube or the container?

ZOE: Yeah, once.

MOLLY BLOOM: How would you describe it?

ZOE: I don't know. It's a bit scary for me. I see it filling up, "What's happening?"

MOLLY BLOOM: And you're like, that's coming out of me and into the tube? But it's so awesome because our bodies can just keep making more blood, which is pretty cool.

ZOE: Yeah.

MOLLY BLOOM: Do you think about your blood on a day-to-day basis? Are you like, "Wow, my blood is so awesome?" Or is it sort of just in the background not really being thought about?

ZOE: Sometimes when I get hurt or just when I'm on the couch and I'm bored, I just think about it.

MOLLY BLOOM: Yeah, whenever you feel your pulse, and you're like, "Oh, that's my blood in there." Yeah, blood tests are pretty common. I've had my blood drawn a lot of times. And a nurse or a phlebotomist, which is a really cool word for someone whose job it is to collect blood samples, a phlebotomist, they can either take a small amount of blood by pricking your fingertip or they may go to a vein in your arm for bigger samples. Before we find out how they do blood tests, let's talk about why the blood gets tested in the first place.

ZOE: If you break your arm, you can get an X-ray to see what happened. Or if you have an infection, a doctor can use an otoscope to see what's going on in there.

MOLLY BLOOM: But there are times when something is going on inside your body and you can't tell just by looking at it or listening to it. Testing your blood can give important clues to figure out what's going on.

ZOE: But why blood? Why not spit or pee or even a big breath out?

MOLLY BLOOM: Sure, those can give us some good info about our health. But when it comes to really understanding how our bodies are doing, nothing beats blood.

ZOE: That's because blood is a transportation system for all the supplies your body needs to do its thing.

MOLLY BLOOM: When you see your blood, it just looks like a deep-red liquid.

ZOE: But it's actually a bunch of things.

MOLLY BLOOM: There are red blood cells, white blood cells, water, proteins, sugars, hormones, salt, and more.

ZOE: All of those are crucial supplies that our bodies need.

MOLLY BLOOM: So our blood needs a way to move around the body and fast. Our thumping, pumping hearts propel our blood through a blood vessel superhighway made up of arteries, veins, and capillaries. Let's start with blood leaving the heart. This blood is full of oxygen from the lungs and it gets pumped into large arteries.

ZOE: They're like a mega highway.

MOLLY BLOOM: From there, blood zips along to medium-sized arteries and smaller arterioles. These are like medium-sized roads that help you get from neighborhood to neighborhood.

ZOE: And finally, the tiny capillaries. These are the little side streets of the body.

MOLLY BLOOM: There, the blood will drop off the oxygen and tissues and organs and pick up carbon dioxide. Then it takes that carbon dioxide back to the lungs through the veins. The carbon dioxide is switched for more oxygen. The blood goes to the heart and starts its journey all over again. These tubes of blood are all over the body because your whole body, yes, every part of it, needs the stuff that blood carries. For example, your cells need energy to do stuff. Where do they get that energy?

ZOE: From food.

MOLLY BLOOM: And how does that energy go from the food in your guts to the cells?

ZOE: Blood.

MOLLY BLOOM: Cells all over your body also need oxygen. And how does your body get oxygen?

ZOE: By breathing.

MOLLY BLOOM: And how does oxygen get from your lungs to those cells?

ZOE: Blood.

MOLLY BLOOM: These are just some of the important things shipped around the body by the superhighway that is our blood. Let's check in with our very own Sanden Totten, who's keeping an eye on morning blood, rush hour traffic.

SANDEN TOTTEN: It's a busy day on the blood superhighway. Blood has places to go and lots of supplies to get around. Thankfully, no backups getting in the way, and traffic is flowing smoothly. Nutrients like sugar, fat, proteins, and the like are hopping on board the blood superhighway in the intestines and getting shuttled all over the place to the cells that need them to get their jobs done. Whoo, boy.

And we're seeing waste get picked up from the cells all over the body and shipped off to the lungs and other ejection sites. That's right, blood cleans your insides. It's a real blood bath for the body. By the way, fun fact, every time you're exhaling, you're getting rid of waste your body doesn't need. Breathing out is like pooping for the lungs. Think on that as you start your day, Molly and Zoe.

Oh, and of course, blood is swinging by the brain, glands, and all sorts of organs, picking up special body chemicals called hormones. These babies tell the body when to sleep, eat, grow, all sorts of fun stuff. And my goodness, is there anything this blood superhighway can't do? What a system, what a day. I've been your eye in the artery. It's Sanden Totten. Back to you, Molly and Zoe.

MOLLY BLOOM: Thanks, Sanden. I have no idea how you got a tiny helicopter in a blood vessel but glad you did.

ZOE: So blood is full of all kinds of things. That's why we can learn so much about what's happening in our bodies by testing it.

MOLLY BLOOM: So let's jump to this pair of listener questions.

MICAH: My name is Micah from Silver Spring, Maryland. My question is, how does a body make blood?

SKYE: I'm Skye from Los Altos, California. And what is blood made of?

ZOE: Blood is made up of two parts, plasma and blood cells.

MOLLY BLOOM: The plasma is what makes your blood liquidy and is mostly made up of water.

ZOE: The blood cells have different jobs depending on what kind they are.

MOLLY BLOOM: Your red blood cells carry oxygen and carbon dioxide around your body, and they make your blood look red.

ZOE: Then there are blood cells called platelets.

MOLLY BLOOM: Which help you stop bleeding when you get cut.

ZOE: And white blood cells.

MOLLY BLOOM: Which help you fight off viruses, bacteria, and other stuff that can make you sick. These cells are made in your bones, specifically in the bone marrow.

ZOE: That's the spongy tissue inside of some of your bones.

MOLLY BLOOM: This liquidy superhighway, quietly thrumming and pumping through our bodies, is very easy to take for granted. You can't really feel it unless you try, but it's quietly keeping us alive.

ZOE: And because of that, it holds a lot of information about how our bodies are doing, which brings us to blood tests.

MOLLY BLOOM: Before we find out how blood tests work, I have a test for your ears. It's time for the--


ZOE: Mystery sound.

MOLLY BLOOM: You ready to guess the mystery sound, Zoe?

ZOE: Yes.

MOLLY BLOOM: All right.


What is your guess?

ZOE: That's a lot of things.

MOLLY BLOOM: What did you hear? What's one thing you heard there?

ZOE: I don't know. There's a lot of wind.


ZOE: Like, things.

MOLLY BLOOM: Yeah, I also have no idea what this is. So we hear it again and see if we can pick anything else out.

ZOE: Yeah.

MOLLY BLOOM: OK, let's hear it one more time.


Mhm, what do you think?

ZOE: I don't know. It sounds like for-- I don't-- I've never been there. I don't know how it's called. But like those giant tubes that you go in sometimes, and you wear a suit, and there's so much wind that it makes you fly.

MOLLY BLOOM: Oh, yeah. It makes you feel like you're skydiving.

ZOE: Yeah.

MOLLY BLOOM: Yeah, I've seen those tubes.

ZOE: Yeah, but I don't really think it's that. It's just my only guess.

MOLLY BLOOM: Yeah, there was like--

ZOE: I mean, it might be a storm or hurricane but doesn't really sound like it.

MOLLY BLOOM: Yeah, there was a lot of shuffling. There was some clicking. Honestly, what it sounded like to me was, I don't know if it's ever happened to you, but like, someone calls you by mistake and their phone is in their pocket. It's kind of what it sounded. Like, someone was just walking around with their phone in their pocket, and they called us by mistake. I think that's what it is. Well, we will hear it after the credits and get another chance to guess and hear the answer.

We are working on an episode all about space. It's huge. It's mysterious. It's extraordinary. And we want you to write a space jingle for us.

ZOE: A jingle is a short, catchy song to tell someone how great something is.

MOLLY BLOOM: So Zoe, what would your space jingle be?

ZOE: Oh, that's a hard one. (SINGING) I love thinking about the Big Bang. It makes me want to sing.

MOLLY BLOOM: That's very, very nice. Listeners, record yourself singing your space jingle and send it to us at While you're there, you can send us mystery sounds, drawings, and questions.

ZOE: Like this one. Why are pretzels shaped like they are?

MOLLY BLOOM: You can find an answer to that on our Moment of Um podcast. It's a short, fun dose of science and facts every weekday.

ZOE: Find it whenever you listen to Brains On.

MOLLY BLOOM: Just Search for Moment of Um.

INTERVIEWER: OK, let's see. Monica Mosquito?


Why don't you take a seat right over there?

MOSQUITO: I'd rather have it here right next to your ear.

INTERVIEWER: Uh, OK. So why do you think you'd be a good nurse?

MOSQUITO: I can flit from task to task very quickly. 1 minute I'm there, the next I'm gone. And I'm a real people person. I love big crowds.

INTERVIEWER: And what would you say is your biggest weakness?

MOSQUITO: My weakness? Oh, that's easy. I care too much about blood.

THEME SONG: Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, Brains On.

ZOE: You're listening to Brains On from APM Studios. I'm Zoe.

MOLLY BLOOM: And I'm Molly. Now, to find out how blood tests work, we're going to visit a place where blood is tested.

ZOE: At a blood school in tiny Bloodthirst with little, tiny, number 2 pencils?

MOLLY BLOOM: Not quite. We're visiting a lab at the Los Angeles County, USC Medical Center.

RIA VERGARA-LlURI: I'm Ria Vergara-Lluri. I am an assistant professor of clinical pathology for the Keck School of Medicine of USC. I oversee the tests that are run in this laboratory for blood tests.

MOLLY BLOOM: To help us interview Ria at her lab, we invited along someone who is very used to asking her questions, her eight-year-old son.

ADRIAN LLURI: My name is Adrian Lluri. When you were eight, like me, were you afraid of blood?

RIA VERGARA-LlURI: I used to be, maybe at 8, but then my brothers would do all sorts of gross things and say ketchup looks like blood, eew. So I steeled myself, and then I got better at not getting grossed out by blood. So I have my brothers to thank for that. Does blood make you scared?

ADRIAN LLURI: Uh-uh, because it's just something that comes out of someone's body. So it's just like skin.

MOLLY BLOOM: The tour starts when Ria opens a heavy-looking door.

RIA VERGARA-LlURI: OK, so this is a really-- it's actually kind of a pretty big operation.

MOLLY BLOOM: When someone takes your blood, it's sent to a lab like this one for testing.

RIA VERGARA-LlURI: So this is the core processing area.

CO-WORKERS: Hi, guys.

MOLLY BLOOM: It's a room about the size of a basketball court. There are lots of people hard at work surrounded by rows of machines. Kind of like an arcade, but instead of games, each machine is used for testing blood. Different machines do different kinds of tests.

ADRIAN LLURI: How many different blood tests are there?

RIA VERGARA-LlURI: Wow, you're asking a very difficult question, because it depends on the laboratory. It depends on the lab. Some labs that are pretty small can probably do a dozen, two dozen tests. Our lab, I haven't even counted, probably does at least 100 different kinds of tests.

MOLLY BLOOM: Ria says they can test blood for all sorts of things. They can see how many red blood cells you have or white blood cells or platelets. They can measure the amount of hormones or minerals. Think of it like a soup. If a soup tastes good, it's because all the ingredients are in balance, not too much of any one thing. It's the same with your blood.

If a soup tastes bad, something must be off. So you can sample the soup to see what the problem might be, too many noodles, not enough carrots, or maybe it's the broth. So you filter out the chunky bits and just taste the liquid. Is it too salty, too thick? This is similar to how different blood tests work. Some count the number of red blood cells or others check your blood broth to see if all the ingredients are in balance. But before you can test it, the blood needs to get to the lab.

RIA VERGARA-LlURI: Here is our pneumatic tube system, so you're going to want to take a recording of these.


The pneumatic tube system, we just received a tube of blood in there.

MOLLY BLOOM: Each tube of blood has a special cap on it. The caps are different colors, depending on the type of test that blood needs. So tubes with a green top get one kind of test, and tubes with a red top get another. They used to be sorted by hand but larger labs like this lab have a special machine called an automation line that helps with that. Someone puts the tubes of blood into the automation line and it's moved along like passengers on a flat, slow roller coaster.

RIA VERGARA-LlURI: So he's loading this specimen. So everything is barcoded so that we don't make mistakes. There's computers that barcode. You see when every time a light flashes, that's the analyzer seeing, "Oh, this is patient X. They want this test done." And every single one is put into the computer, and the computer knows where a tube is at any given moment in time.

MOLLY BLOOM: Once the blood is sorted and prepared by these machines, it moves on along its little ride to get specific tests done. Some of the blood goes to a machine that has two chambers in it or two containers. Ria says there's a very teeny hole in the wall between these two containers. They put the blood in one container and it starts to leak into the other side through that hole.

RIA VERGARA-LlURI: And every time it goes through a hole and a chamber, every time it feels a blip go through the hole, it will count the number of particles or cells that go through there. And the larger the blip, the bigger the cell. The smaller the blip, the smaller the cell. So it will count red blood cells going through, white blood cells going through, and that's how we figure out how much you have in a certain set volume of blood.

MOLLY BLOOM: Another machine puts some blood in a little box with a tiny, metal ball in it. The ball is wiggled around back and forth in the blood until the blood clots and gets hard. That stops the ball from moving. This test measures how fast blood clots. If the blood takes too long to clot, that means there's a problem with the blood. Ria says even though the tests are often done by machines, people need to be there to make sure the machines work right and to make sense of the results.

RIA VERGARA-LlURI: I think most people think, let me send a tube of blood into the lab. It'll go into a box, and out come the results. There's actually a lot of work that goes into it, and a lot of people have to do the right thing in order for the right result to come out.

ADRIAN LLURI: What's your favorite part about the job?

RIA VERGARA-LlURI: Oh, so many favorite parts. I love the problem-solving and helping patients get an answer so that their doctors know what to do about it. And then I love the people also that help to make the lab really, really good and make sure it turns out really good results.

ADRIAN LLURI: Thanks, mom, for showing me your lab.

RIA VERGARA-LlURI: Thank you for being here.


MOLLY BLOOM: We've been talking all about blood, what's in it, the amazing things it does, and what it can tell us about our health.

ZOE: Yeah, blood is super important. And sometimes, when a person is sick or gets hurt and loses blood, doctors will give them fresh blood. It's called a blood transfusion.

MOLLY BLOOM: That blood comes from healthy adults, who volunteered to donate it. A trained nurse will take a pint of blood. That's about the same amount as two milk cartons in your school lunch. But don't worry. Your body will naturally make more.

ZOE: That donated blood gets put in a sealed bag and is shipped to hospitals all over the country.

MOLLY BLOOM: But there are two big challenges. Blood only lasts 42 days before it goes bad and it has to be kept cold that entire time.

ZOE: That can make it really hard to ship blood where it's needed like small towns far away from hospitals or remote islands in the middle of the ocean.

MOLLY BLOOM: So scientists have been trying to make artificial or fake human blood in the lab. Turns out, it's a lot harder than it sounds. You have to make something that doesn't just look like blood, it has to act like it.

ZOE: Remember, blood is like a big pot of soup full of different parts all doing different things.

MOLLY BLOOM: Like platelets to help us stop bleeding and white blood cells to fight off infections plus a lot of other stuff.

ZOE: And it's tough to make fake blood that does all of these things. So scientists have mostly focused on making blood that does one thing, pick up oxygen from our lungs and move it around the body. But even that's tricky.

THEODORE THOMAS: Actually, it's not that difficult at all.


MOLLY BLOOM: Has he been there the whole time?

THEODORE THOMAS: I'm awfully sorry to startle you, but I just needed to interject. You see, making blood is quite easy. I should know. I'm a physician.

MOLLY BLOOM: Wait, you're Theodore Gilyard Thomas.

THEODORE THOMAS: Ah, I see my reputation precedes me.

ZOE: Well, you are wearing a name tag on your lab coat.

THEODORE THOMAS: I have pioneered a new substitute for blood.


Oh, Betty, shh, not now. I'll take you straight home. Don't think I won't. Now then, as I was saying, I have pioneered--


Oh, for heaven's sake, it's milk. Cow's milk is the substitute for blood. You'll notice it looks very similar to that fatty, white liquid in your blood, the kind with all your white blood cells.


Oh, yes, Betty. Milk is incredible, and not just in your cereal. All you have to do is inject fresh milk from a young, healthy cow directly into a patient's veins. Just as good as blood.

ZOE: Actually, that didn't work. You tried those experiments in the late 1800s, and milk wasn't a good replacement for blood. It doesn't carry oxygen.

MOLLY BLOOM: Yeah, there have been a bunch of other scientific advances when it comes to making artificial blood in the lab. Milk wasn't a great option, but--

DR. WILLIAM: Of course, milk didn't work. What poppycock. But I believe I've solved the mystery.

ZOE: Who's this guy now?

DR. WILLIAM: Why? Dr. William or Amberson. I'm only one of the most accomplished physicians of the 1930s. Now listen closely, because I have unlocked the secret and found the perfect substitute for human blood. It is-- drum roll, please.


--ox blood.

MOLLY BLOOM: Did he just say ox blood.

DR. WILLIAM: Ox blood. Simply withdraw the blood from a healthy ox. Take out the hemoglobin. That's the protein that carries oxygen around the body. Then mix that hemoglobin with salt, and voila.


Well, I'd never. How rude. Were you raised in a barn?


ZOE: Betty's right. Ox blood didn't work either.

DR. WILLIAM: I mean, oh, yes. There were some issues with the early tests, but we just have to work out the kinks. Pure hemoglobin from oxen. That's the way to go.

MOLLY BLOOM: Trying to replace blood with pure hemoglobin isn't the solution either, because, it turns out, hemoglobin is cocooned inside our red blood cells like the jelly inside a donut.

ZOE: And if you take it out of your cells and inject it straight into the body without the outer shell, it's toxic. It can damage our organs.

DR. WILLIAM: Oh, so if milk didn't work and ox blood was no good, oh, should we just give up? Just call our mothers and say, "Well, you were right, mom. I should have joined the family dough-making business instead of becoming a doctor."?


ZOE: Actually, scientists have made a ton of progress when it comes to developing artificial blood. Some researchers in Maryland and Missouri have even created a fake red blood cell that can carry oxygen around your body.

MOLLY BLOOM: It would come as a dry powder. So it would last a lot longer than fresh blood. The idea is that you just mix it with water to make a blood substitute.

ZOE: It's still being tested and it won't be able to replace donated blood completely. So we'll still need healthy adults to give blood. But scientists say it could help save lives in the future.

MOLLY BLOOM: Human blood is so important that scientists have spent hundreds of years trying to figure out how to make it. They haven't quite cracked the mystery yet. But that's just the nature of science, lots of experimenting. And they get closer every time.

THEME SONG: Brains on.

INTERVIEWER: Mr. Vamp Ear? Mr. Vamp Ear?

VAMPIRE: It's vampire.


INTERVIEWER: All righty, great. I just have to tell you, Mr. Vamp Ear, your job application was quite unusual. I mean, you are certainly the first applicant we've had at this hospital with more than 900 years of work experience.

VAMPIRE: Yes, well, thanks so much.

INTERVIEWER: I see that you prefer the night shift and that you'll require frequent coffin breaks. I'm guessing that's a typo. You must mean coffee breaks.

VAMPIRE: Sure, sure. How silly of me, huh? Coffee breaks, of course.

MOLLY BLOOM: Blood is crucial to every bodily function.

ZOE: It carries the supplies our bodies need and helps us dispose off waste.

MOLLY BLOOM: Testing blood can give doctors important clues about your health.

ZOE: Sometimes a person gets hurt or can't make enough blood on their own, so they need people to donate blood.

MOLLY BLOOM: But scientists are working on making a fake version of blood that could last longer and help more people who need it.

ZOE: This episode was produced by Molly Bloom, Sanden Totten, and Sheila Shahla Farzan with help from Rose Dupont, Anna Goldfield, Ruby Guthirie and Marc Sanchez, Anna Weggel, Abran Moh de Selassie, and Nico Gonzalez Wisler.

MOLLY BLOOM: This episode was sound-designed by Rachael Briz. We had engineering help from Laura Marina Boria. Special thanks to Juan Velasquez, Daniel Rivera, Stuart Bloom, and Eric Ringham. The executives incharge of APM Studios are Chandra Kavati, Alex Shepherd, and Joanne Griffith.

ZOE: Brains On is a non-profit, public media program. There are tons of ways you can support the show.

MOLLY BLOOM: Yeah, head to, where you can donate.

ZOE: Listen to past episodes.

MOLLY BLOOM: And submit questions for future shows. OK, Zoe, are you ready to hear the mystery sound again?

ZOE: Yes.


MOLLY BLOOM: Any new thoughts?

ZOE: No.

MOLLY BLOOM: Yeah, that's a really tricky one. So yeah, I thought it was a phone in a pocket. You thought it was someone skydiving in a tube.

ZOE: Or maybe it could actually be actual skydiving. But--

MOLLY BLOOM: Oh, yeah.

ZOE: I think if it was actual skydiving, someone would be screaming.


MOLLY BLOOM: Yes, I think you're right about that.

ZOE: Yeah, I actually noticed it actually kind of sounds like people throwing things.

MOLLY BLOOM: OK, nice. OK, so we're hearing people throwing things. But let's take a random guess about what they're throwing.

ZOE: I don't know, planks.

MOLLY BLOOM: Cool. You want to hear the answer?

ZOE: Yeah.

MOLLY BLOOM: OK, here it is.

MARGO: Hi, my name is Margo, and I'm from Athens, Georgia, and that sound you've just heard was the bats going crazy that live in our attic.

MOLLY BLOOM: What? Excuse me? Bats in an attic? OK, so we thought it was skydiving, a phone in a pocket, people throwing stuff. It turned out to be bats flying around a lot. OK, so I think when you said throwing stuff around, you were kind of close, because things were getting thrown around, but it was just bats throwing themselves around.


Now it's time for the Brains honor roll. These are the incredible kids who keep this show going with their questions, ideas, mystery sounds, drawings, and high fives.


That's it for this episode of Brains On.

ZOE: Thanks for listening.

Transcription services provided by 3Play Media.