How do noses work? Objects give off tiny amounts of tiny molecules into the air. When just a few of these molecules get up your nose, they dissolve in the mucus up there. Some molecules come into contact with special receptors on what’s called your “olfactory membranes.” Each nostril has a membrane, and each membrane is only about the size of a postage stamp. The membranes hold millions of receptor cells, each of which are ready to send messages to the brain about the molecules that go up your nose.

Fluids are cool; they ooze and swoosh. Whatever container you put a fluid in, that fluid will take the same shape. Milk poured into a pitcher forms to the shape of the pitcher. If you pour it into a glass, it takes the shape of the glass. You just can’t do that with a boulder. But with the right container, you could pour liquid rock from below the Earth’s crust. Fluids still act like fluids, even halfway to the center of the Earth.

Dirt, sand, and rock from the Earth’s surface gets blown, sliced, torn, swallowed and distributed all over the world. What was yesterday’s hill is tomorrow’s flat plain. The planet looks a lot different than it did when it formed four and a half billion years ago. The force of erosion, the slow wearing away of the land, has never ceased.

Music is the art and science of expressing ideas and feelings through sound. A sad song can say more about how someone feels than most words, and a familiar song can make crowds clap together and feel like one happy family. Whatever the emotion, music seems to have a way to communicate it. The music we listen to today is the result of years of experimentation with sounds. As people figured out what they liked best, they invented instruments that could play their favorite tones and developed popular rhythms, or patterns of beats. Each note of music, and every tone of each instrument is a sound wave. Some sound waves sound great together. Some not so good. Getting the exact soundwaves in the pattern you want – now that’s science.

Bill Nye looks at how the brain controls the body and stores information

In Bill Nye the Science Guy: Forests, Nye shows students the levels of a forest, which include the canopy, the under story, and the floor. His special guest is Nalini Nadkarni, who has no qualms about going high up in the canopy to check out the wildlife and other happenings there

Each planet is different. They are all different sizes – Pluto’s the smallest, and Jupiter’s the biggest. They come in a variety of colors – Mars is covered with rust, so it looks red; the methane (cold natural gas) in the atmosphere of Uranus makes it look blue; and Saturn’s colorful rings are made of icy rock. As far as we know now, Earth is the only planet in our solar system that is home to living things.

Outer space is full of stuff. We’re not just talking about planets and moons. There are some bits and pieces, too small to be noticed most of the time that float around and occasionally run into all those planets and moons. Comets and meteors are the big bits of dirt, rock and ice that inhabit our Universe. More than just high-speed space chunks, comets and meteors carry important information about the history of our Universe.

Did you know that the Concorde moves 300,000 times faster than a land snail? Or that a giant redwood can be as tall as a 35-story apartment building? The only reason we can make these comparisons is because people have measured these things. We don’t compare jets and snails every day, but we do rely on measurement constantly. When you take your temperature, you find out how it compares to the temperature of someone who is healthy. When you bake brownies, you’ll need to measure the ingredients first to make sure they turn out tasty. Using measurement, we can make useful comparisons of distance, time, mass, and temperature.

Storms are big, loud, and often accompanied by rain, snow, sleet, or hail. Where do these wild, dangerous, and necessary tornadoes, hurricanes, and thunderstorms come from? Storms happen when huge different air masses collide. Along the border of these air masses, water vapor condenses into clouds, strong winds form, and the clouds rub against each other with the ground often becoming electrically charged waiting to send lightning bolts across the sky. What starts out as a placid summer day turns into two air masses boxing it out 10,000 meters up.

Forensic scientists try to find out the who, what, when, where, and why of events in the past – crimes. Most forensic scientists work in police labs. They collect evidence from the scene of a crime and analyze the evidence in a lab. Forensic scientists look for clues that will help them solve a crime. Fingerprints, footprints, hair, blood, and traces of gunpowder can be helpful evidence. Forensic scientists use all sorts of scientific instruments to analyze even the smallest bit of hair or the tiniest chip of paint. By scientifically testing evidence from the crime scene, and by knowing about evidence from past cases, forensic scientists can piece together what happened, to figure out who did what, and to help police catch a criminal.

Things can appear to be moving, when they really aren’t. Sometimes an object might seem to be at rest, even when it is in motion. It’s all relative. Relative motion, that is. How things appear to move depends on how you, or any observer, happens to be moving. So, if you’re on a bus looking out a window into another bus, and your bus begins to back up slowly, you may think the other bus is moving forward, when really it’s not moving at all. That’s motion in motion. It happens all around us all the time.

Surf's up! Get the current information as Bill Nye explains why oceans are salty and explores the ocean currents. Go with the flow of ocean currents with Bill Nye the Science Guy. Most of the Earth is covered with water - we're talking 71% of the entire Earth, and most of that water is in oceans. It depends how you count, but you can say that there are five oceans on Earth - the Atlantic, the Pacific, the Indian, the Arctic, and the Antarctic. They are all connected into one World Ocean by the flow of ocean currents. Ocean water is moving around all the time. Some of the moving water forms rivers in the ocean. Oceanographers, scientists who study oceans, call these rivers of ocean water "currents". Currents help sea animals move around, they bring up deep ocean water with lots of nutrients for small animals to eat, and they push warm and cold water around, creating different climates in the oceans. As the sea surface gets warmed by the Sun, water evaporates, but salt stays in the sea.

Bill Nye teaches us about reptiles.

We live on top of rocks – the Earth’s surface. There are three basic types of rocks — igneous, sedimentary, and metamorphic — and each type is made a different way. Igneous rocks are made from cooled lava. Sedimentary rocks are made from small pieces of other rocks stuck together. Metamorphic rocks are formed when other rocks are heated or pressed, or both. One type of rock can change into another type of rock as the Earth’s surface shifts and changes. It takes the right conditions and a lot of time.

Friction is a force that slows moving things down and turns the moving energy into heat energy. When two things rub together, like your bike tires and the road, friction between them slows you down. There’s also friction in the metal parts of the wheel’s hub – at the center. There’s even friction between the fibers and rubber of the tires themselves as they flex and roll. That’s why you eventually stop rolling when you stop pedaling. Rough things make more friction than smooth things. Rubber shoes on a clean wooden basketball floor create more friction than do hard metal skate blades on smooth ice.

Mammals - They're (sometimes) big, they're hairy, and they're warm-blooded. From human being to moose and from cats to rats, Bill Nye explains what it takes to be in the mammal family.

A lot of things spin – bike wheels, footballs, hard disks in your computer, and even the Earth – they’re all twirling around. Spinning things have inertia, which means they keep spinning unless something slows them down. Bike tires keep spinning until you put on the brakes. A football spirals through the air until you catch it. The Earth keeps on spinning 24 hours a day, seven days a week. It’s been spinning for over four billion years.

More than 22,000 different species of fish live in the oceans, lakes, and rivers of the world. Fish come in all shapes and sizes. Some eat water plants, some eat other fish. Lampreys and some jawless fish suck onto other fish for food. Stone fish live on ocean bottoms and camouflage themselves as rocks. Puffer fish blow themselves up like a balloon, only they’re covered with spines. There are tons of strange and cool-looking fish everywhere.

Atoms are reeeeally small. They are so small that you can’t see them with just your eye. It takes as many as 10 million of them side-by-side to measure a single millimeter. In fact, atoms are the smallest pieces of “stuff” that are still considered “stuff.” If you take something and break it into tiny pieces, and then break it into tinier pieces, and keep going, the smallest part you’d be left with (and still have the same substance that you started with) is an atom. Atoms are the building blocks of all matter. Everything is made of only 109 different kinds of atoms, called elements. 92 of these elements occur naturally, but the rest of them – ones like Technetium and Promethium have only been found in distant stars and Californium and Einsteinium – are only made in laboratories. A molecule is born any time two or more atoms combine together. English

Ocean exploration is a tricky, risky business since humans can’t naturally survive under the ocean. Ocean explorers are constantly inventing new tools to help them dive deep into the sea. Over the last few hundred years or so, and especially in the last few decades, we humans have come up with all kinds of new ways to study the ocean. Even so, the ocean remains largely unexplored. It’s huge, cold, salty, and deep. Ocean exploration helps us understand our planet, and may help us solve the mystery of how life started on Earth.

The relationship between the Earth, the sun, the wind and the weather. Guest: "Today" weather reporter Willard Scott.

When you push something, you’re using pressure. Pressure depends on two things – the power of the push and the area that’s being pushed on. A push on a small area makes more pressure than the same size push on a big area. Pushing hard on something creates more pressure than a little nudge, naturally.

Energy, things like light, heat, and sound, moves in waves. You’ve probably seen waves in the ocean, or ripples when you throw a rock in a pond. Moving energy is not like the wave you do with your hand.

Scientists believe that birds evolved from reptiles. Birds have backbones, and they lay eggs, but they’ve developed a unique feature that sets them apart from all other animals – feathers. Feathers are made of the same stuff human fingernails and hair are made from – a protein called keratin. Feathers, combined with lightweight bones, powerful wings and strong hearts let birds fly.