Most dead animals and plants break up, get decomposed, and become part of the soil, but some turn into fossils. A fossil forms when a plant or animal dies, and gets buried. If conditions are right, water gets into the fossil bed, and chemical reactions preserve the impressions for thousands or millions of years. There are different types of fossils — imprints of animals, black carbon outlines, hardened bones, or actual animals and plants that have been trapped in ice or hardened tree sap.

Dirty water, land, and air are a result of pollution. People are the only animals on Earth that make pollution. Garbage, burning fuel, chemicals, sewage, oil, and pesticides are all human-made things that make the Earth’s atmosphere, water, and soil unclean. Humans are even leaving trash in space, such as broken satellites, pieces of metal, paint from rocket skin, and even cameras and toothbrushes. Much of the junk people make and leave behind hurts plants, animals, you and me.

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

Water is massive; rivers are powerful. As rivers flow downhill, they wear away rock and soil to form canyons or winding curves in the land, called meanders. Sometimes rivers fill and overflow their banks. Rivers with too much water create floods that can carry away plants, trees, buildings and boulders. Rivers and streams support most of the ecosystems on land.

Flowers are an important part of many plants. Plants use flowers to make other plants – to reproduce. Flowers have special parts, called stamens and pistils. When pollen from the stamen finds its way down through the pistil, the flower is pollinated, and seeds start to grow. The seeds eventually find their way to the ground, the seeds sprout, and more plants are born.

Volcanoes are mountains made from molten rock. The Earth’s crust is divided into big slabs, called plates, which are slowly moving all the time. The plates are floating on the Earth’s mantle, a layer of gooey hot rock that flows like maple syrup. Some places in the mantle, the rock gets very hot and nearly liquid. It’s called magma. Sometimes the magma reaches the Earth’s surface and forms a volcano.

Be sure to get this straight: spiders are not insects, they’re arachnids. Spiders have eight legs, and insects have only six. Spiders have two body parts, a head and an abdomen, while insects have three body parts, a head, a thorax, and an abdomen. Insects have antennae, and spiders do not. Some insects sting. All spiders have fangs and venom. There are almost certainly a few spiders in the room with you right now.

Archaeologists are kind of like detectives. They’re scientists who snoop through old or ancient people’s things to find out what life was like thousands of years ago. Archaeologists find ancient cities, tombs, and temples by taking aerial photographs of Earth, by reading old documents, or by just looking at the shape of the land. When they think they’ve found a site, the archaeologists pick up a shovel and start digging. When archaeologists get close to an object, they dig very carefully. Sometimes they dig with nothing but a toothpick and a paintbrush. Whew!

Time affects every living thing on Earth. Trees shed their leaves. Some animals only come out at night. There are even insects that only emerge every 17 years. Days, hours, minutes, and seconds – all of these were invented by humans. Humans came up with these units of time to organize their lives and to study the world. One of the first ways humans told time was by noticing the difference between daytime and nighttime. Humans use the Earth revolving around the Sun to divide time into years and seasons. Months are based on the movement of the Moon around the Earth. A day is when the Earth spins completely around its own axis.

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.

Earthquakes happen when pieces of land in the Earth’s crust scrape together. The crust of the Earth is made of big slabs of land called plates that are constantly moving just a little bit. The plates scrape by one another, and sometimes they don’t move smoothly. An earthquake happens when the plates get unstuck suddenly and jerkily slip past each other. The majority of earthquakes occur along plate boundaries such as the boundary between the Pacific Plate and the North American plate. One of the most active plate boundaries for earthquakes is the massive Pacific Plate commonly referred to as the Pacific Ring of Fire. The fire comes from the volcanoes that form near the edge of the plates.

About 20% of the Earth is a desert. Deserts are places that get very little precipitation (rain or snow) each year, and that makes them extremely dry. Deserts cover big areas of land. The biggest desert, the Sahara, extends from North Africa to Southwest Asia and is 13 times the size of Texas. Some parts of the Sahara get as little as 2 millimeters (0.08 inches) of water a year.

Frogs, toads, salamanders, newts, and caecilians (worm-like animals that have backbones) are all amphibians, animals that spend part of their lives in water and part on land. Amphibians are slimy. Amphibians are cold-blooded that means their body temperature changes with the temperature outside. And as amphibians grow up, they go through metamorphosis.

Worms, squid, clams, and flies are spineless creatures. They’re not afraid, they’re invertebrates – animals that don’t have backbones. Invertebrates are everywhere. You can find invertebrates in the sea, in freshwater, and on land. There are about 30 times more invertebrates than vertebrates on Earth.

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

Learning about skin science is no sweat. It's gigantic. It's gargantuan. It's your skin. It's your body's biggest organ. If you could lay your skin out flat, it would cover about one and a half square meters. Your skin stops you from drying out, protects you from the weather, and keeps bacteria and viruses from getting inside your body. Your skin is also your personal air conditioner and heater all in one. Sweating cools you off. When you're hot, glands in your skin push a mixture of water and other chemicals onto the surface of your skin. When the water evaporates, it takes some of the heat with it, and you're cooler. When you're too cold, your skin muscles start twitching. Shivering makes your body warm up. Without skin, you wouldn't be able to feel the difference between a sheet of paper and a wool blanket. There are thousands of touch receptors inside skin. When you touch the remote control, the receptors send information about the remote's temperature, thicknes

Lighten up. It's the ""Light and Color"" episode. Without light, we wouldn't be able to see. It would be like living in a room with no windows, doors, or lamps. There's an old saying, ""We don't see things; we see light bouncing off of things."" We see things, and colors, when light bounces off things and into our eyes. White light, like the light from the Sun, is made up of all the different colors of light blended together. When white light hits something white, almost all of the light bounces into our eyes, and we see the color white. Things are different colors because some light bounces off and other light gets absorbed. An orange is orange because it absorbs all different colors of light except orange light. Grass is green because it absorbs all different colors of light except green light. Bill Nye's lab coat is blue because it absorbs all different colors of light except blue light. All colors, including black, are made in the same way. It's just a matter of ref

It's time for Bill Nye to shed a little light on electricity. Electricity might seem mysterious, but once you understand the science the light goes on (so to speak). You flip a switch, and the lights turn on. You push the play button, and your personal stereo starts playing music. When you flip the switch or push play, you start a flow of electrons. Electricity is the flow of electrons, and electrons are very tiny charged particles. Electrons are found in atoms, the tiny pieces that all stuff is made from. We can make electrons flow in two ways. Batteries make electricity by mixing up chemicals -- making a chemical reaction that forces electrons to move in a path from the battery to the personal stereo and back to the battery. Electricity that turns on lights in your home is made by power plants. Most power plants use big machines called generators to make electrons by twirling wire in a magnet. The magnet makes electrons in the wire move around, creating electricity.

In this show, you can Bone up on Muscles. When you clicked on the Nye Labs web site to read this, you used your bones and muscles. Without them, you can't click, surf, or even sigh. Bones and muscles work together, or you aren't going anywhere. Muscles always pull, even when you push on something like a door somewhere in your body your arm and leg muscles are in tension. They are all attached to bones, and those bones are pushing; they're in compression. By pulling on bones you can breathe, talk, and move all over the world. Your bones support your weight like beams of steel or wood. They're stiff and strong. Rigid as they might seem though, they do flex. And, if you bang one hard enough, it swells up. You have a lump. That's because bones are full of blood vessels. Bones are not solid like rocks or skeletons in a dinosaur museum. Bones flex and grow. In fact, putting healthy amounts of stress on your bones is good for them.

Bill Nye's not here to bug you - he just wants to tell you about insects. Do you know when you're looking at an insect? All insects have six legs, three body segments, antennae, and an exoskeleton. Insects don't have bones. Instead, they have hard shells called exoskeletons. Like a little suit of armor, an exoskeleton protects the insect's body and also keeps it from drying out. Although people call any crawling critter with an exoskeleton a "bug", the "true bugs" are insects that have special mouth parts for piercing and sucking. And, spiders are not bugs or even insects. They're built differently with only two main body parts and eight legs instead of six. If you think you have a wild time growing up, take a look at an insect's life. Most insects go through at least four stages of growth -- egg (little round thing), larva (a bit like a worm), pupa (insect in a cocoon), and adult. It's a long road to maturity for an insect. Everyone's buzzing about the "Insects" episode. Don't miss it

Bill Nye's going to use the force to pull you into the world of balance. A force is a push or a pull. You can feel a force when someone pushes you. You can use a force to pull a door shut. Anyone can make forces by pushing and pulling, and you don't need to be Luke Skywalker to use a force. In a game of tug-of-war, if the pull of your team is the same as the pull of the other team, the forces are equal. The two teams are in balance, and the rope doesn't budge. Things are in balance when forces that are pushing or pulling them are equal. If your tug-of-war team pulls harder than the other team, the forces are not equal. The other team falls all over the place. Unequal forces make things move and twist. A lot of things are designed to take advantage of unequal forces. Wrenches, screwdrivers, door handles, and water faucets use forces made by you to do work. A well-balanced science diet starts with Bill Nye.

Whales, dolphins, otters, walruses, and orcas are just like us, they’re mammals. Well, they’re not just like us. They live in the ocean. They breathe air, have hair, nurse their babies, and they are warm-blooded. They keep the same body temperature all day. To do that in the ocean isn’t easy. Water soaks up heat, so the ocean is really pretty cold. Marine mammals have all sorts of ways to keep warm. Whales, dolphins, and walruses have thick layers of fat called “blubber.” It’s great insulation. It holds their body heat keeping them warm in the cold ocean. Sea otters have thick layers of fur that cover their whole bodies. Otters fluff their fur to trap air between the hairs. It helps them float, it the air keeps them warm even when they dive deep hunting for food. These adaptations make it possible for marine mammals to live all over the world’s oceans.

Don't just go with the flow. Settle down on the crust. Imagine a world without any crust. There would be no pies, just goopy filling, no bread, no hamburger buns, and no you or me. That's right. You, and every living thing we know of, live on or in the Earth's crust. And, living things need the Earth's crust to survive. Let's look at the science of the surface. By carefully studying the Earth's surface, scientists have discovered that the Earth is made up of gigantic layers. At the center of the Earth, there is a core – a big ball of solid metal mostly iron. The core is surrounded by a layer of liquid iron and other minerals. We usually just call it the outer core. The next layer, around the outer core is called the mantle. You may have seen a mantle above a fireplace. Well, the mantle is above the Earth's hot core places. The mantle is gooey hot nearly melted rock that flows the way asphalt does on a hot summer day. Scientists often say that the mantle is plastic. It