Unit 1- Sand
If you look around you, you can find sand very easily. Sand comes from rocks. Each grain of sand is less than 2 millimeters in diameter. Some smaller sand feels like flour. There are many different colors of sand. Some sand is white, and it can be found in tropical areas. Some sand is black, and it can be found in volcanic areas. Also, some sand is green, and some sand is yellow.
Unit 2- Mars
Mars is a planet. It is next to the Earth. Its size is about one fourth of the Earth. Mars is not far from the Earth, but the environment is very different. Because Mars is far from the sun, Mars’ average temperature is lower than the Earth. Mars does not have water. There is no oxygen. Therefore, there are no living things on Mars at all.
Unit 3- The Backbone
The backbone is series bones in the human body. It supports people’s backs. Without a backbone, people cannot stand up, sit down, or walk. It is one of the most important bones in the human body. It is also called a ”spine.” Do you know how a backbone is formed? It is made of many small bones. There are usually 29 small bones in the backbone.
Unit 4- The Jungle
Have you ever been to a jungle? A jungle is an area with high temperatures. Also, there is a lot of rain. Usually, rain forests are also called jungles. There are various kinds of plants in jungles. So, jungles produce a large amount of oxygen. Where are famous jungles?The Malay Peninsula, Borneo, and the Amazon have world famous jungles.
Unit 5- Moths
We can find moths all over the world. There are 180,000 different kinds of moths. Moths vary in sizes. Some moth’s wings are only 0.4cm long. On the other hand, a big moth’s wings can be up to 14cm long. The average wing size is about 4~5cm long. Almost every moth is active during the night except for a few kinds. Moths flock together around lights at night.
Unit 6- Lightning
People can see lightning quite often. Lightning is a bright flash. It comes with a thunderstorm. All thunderstorms make lightning. Before people hear the sound of thunder, they see lightning. Lightning is very dangerous. Lightning is about 54,000oF. Also, lightning kills and injures more people each year than hurricanes or tornadoes.
Unit 7- Fossils
Fossils are the remains of animals or plants. They are usually inside of rocks. They are typically more than 10,000 years old. Fossils are made by sudden changes on the Earth like volcanoes and tsunamis. Animals and plants are buried in soil by these sudden changes. Then, they become rocks. The oldest fossil is about 4 billion years old.
Unit 8- Forces
A force is a push or a pull. A force gives an object the energy to move, stop moving, or change direction. Here are some good examples of force. When you write with a pen, you are creating a force. When you pedal your bike, you are creating a force. When you blow your nose, chew your gum, or swim in a pool, you are creating forces.
Unit 9- Whales
Whales are very large mammals, and they live in the sea. They breathe air into their lungs. They feed their babies milk, and they have some hair, too. There are more than 100 kinds of whales in the world. The average size of whales is over 4~5 meters long. Whales are categorized as endangered species. This means catching a whale is illegal. So, people have to protect whales.
Unit 10- Reptiles
Reptiles have scales on their bodies, and they breathe air. There are various kinds of reptiles. They are snakes, alligators, lizards, and turtles. The size of reptiles varies. The smallest reptiles are geckos. It is about 1.6 cm. However, one of the biggest reptiles is the saltwater crocodile. It can grow up to 5.5. Meters long. And it weighs over 1,000 kilograms.
Unit 11- Gases
There are three different kinds of matter. They are solids, liquids, and gases. Gas has no shape, so you can’t touch gas. Gas moves very freely. Gas can change into a solid or a liquid when the temperature gets too low. On the other hand, a solid can change into gas when the temperature gets too high. Is there a good example of these changes? Of course, it is dry ice!
Unit 12- Hurricanes
A hurricane is also called a tropical cyclone, typhoon, and tropical storm. A hurricane is a violent storm. It makes strong winds and rain. How big is a hurricane? How fast is a hurricane? The average radius of a hurricane is from 207 miles to 414 miles. The speed of a hurricane is from at least 74 miles per hour to 195 miles per hour.
Unit 13- Roles
A role describes what function a person has in society. People have their roles to perform. For example, soldiers’ roles are to protect their country. Teachers’ roles are to teach students subjects and to lead students in the right direction. Doctors’ roles are to treat sick people. Police officer’s roles are to help people in trouble. And without question, students’ roles are to study and learn.
Unit 14 – Capitals
The capital of a country is the city where its government meets. The capital of the U.S.A. is not New York City but Washington D.C. Washington D.C. is much smaller than New York in population and size. But the capital of the U.S.A. is Washington D.C. What about China? It is not Shanghai, but Beijing. What about Japan? Japan’s old capital was Kyoto. However, Japan’s current capital is Tokyo.
Unit 15 – Legends
Each country has its unique legends. Greece is rich in legends. Greece has many famous legends about gods and heroes. Zeus was believed to be the god of the sky. Northern Europe is also famous for many legends and myths. Norway and Sweden have many legends about their kings and heroes. Sometimes, some legends are the main topics for movies, such as The Lord of the Rings.
Unit 16 – Islands
An island has many different characteristics. The first thing is climate. An island’s climate is usually milder. So islands are much warmer in winter. For example, Great Britain is an island. So Great Britain is much warmer in winter. Another characteristic is people’s food. It is very easy for people on an island to catch fish. So, there are many kinds of fish on the menu on islands.
Unit 17 – Judges
A judge works at a court. A judge hears people’s arguments. Then the judge decides what is right and wrong. What is a judge called in a court? In the United States, a judge is called “Your honor” or “Judge.” In the United Kingdom, a judge is called “My Lord,” “My Lady” or “Your Honor.” A judge is one of the most powerful people in the court.
Unit 18 – Technology
Technology means the knowledge of using a tool or a machine. Technology makes our lives convenient and easy. Without washing machines, we have to wash our family’s laundry by hand. Without a telephone, we cannot communicate with people far away. Without a computer, we cannot search for information easily. What else is new technology? It includes robots, wireless computers, and MP3 players
Unit 19 – Mines
People get different kinds of materials from different mines. Gold comes from a gold mine. Copper comes from a copper mine. And coal comes from a coal mine. When people think of mines, they imagine a big mountain. However, some people find a big mine under the sea. What is the oldest mine in history? It is “Lion Cave” in Southern Africa. It is about 43,000 years old
Unit 20 – Markets
What do people do at a market? People can buy and sell goods at a market. A long time ago, each town had a market. In this market, farmers could sell crops and animals. The farmers could buy food and clothes at the market, too. Today, there are different forms of markets. They are shopping centers and on-line shopping malls.
Unit 21 – Rachel Carson
Rachel Carson was a marine biologist and a nature writer. She really cared about nature and the environment. She spent a lot of time reading and writing books when she was young. She always wanted to be a writer, and she published her first book at age 10. “The Edge of the Sea” was one of her bestsellers. It was written in 1955, and it is about ocean life.
Unit 22 – Chicago
Chicago is one of the famous cities in the United States. Chicago is very famous for modern buildings. The Sears Tower is in Chicago. It is one of the tallest buildings in the world. It is 443 meters tall and it is a 110-story building. Another tall building in Chicago is the John Hancock Center. It is 344 meters tall, and it is a 100-story building.
Unit 23 – Railroads
Do you often travel by train? It is a very interesting experience. The history of the steel railroad is not that old. It is about 200 years old. Before that, people had a very hard time to travel far away. At that time, people had to travel by horse or walk. Believe it or not, the very first railroad was made with stone in Greece during the 6th century B.C.
Unit 24 – Suburban Areas
An urban area is a city or a town. A suburban area is a place around the city or town. An urban area usually has a lot of people. It also has many convenient facilities, such as movie theaters and big stores. On the contrary, in a suburban area, there are big houses and natural areas. Do you prefer living in an urban area to a suburban area?
Unit 25 – Ruler
A ruler is a very useful tool. It can measure the length of an object. There are many different kinds of rulers. Rulers are made of plastic, stainless steel, and cloth. We use a plastic ruler in the classroom. A stainless steel ruler is usually used in a factory. Why would you use a cloth ruler? They’re used because cloth rulers can be bent easily.
Unit 26 – The Quarter
The quarter is an American or Canadian coin. How much is a quarter? A quarter is equal to 25 cents. It is worth one fourth of a dollar. When was it made for the first time in America? The first quarter was made in 1796. Today, its size is 0.956 inches in diameter. It weighs 5.67 grams. Do you know that is costs 11 cents to make one quarter?
Unit 27 – The Equal Sign
Do you like math? You probably saw an equal sign in math. The equal sign (=) is a symbol in math. It is used to show that things are the same. When was the equal sign made? Who made it? It was invented by Robert Recorde in 1557. How do you read ‘10+10=20’? It is read as “Ten plus ten is equal to twenty.
Unit 28 – A Cup
A cup is a kind of unit. It is used to measure how much something holds. One cup is equal to 8 ounces. It is commonly used in the United States and Japan. However, it is rarely used in the United Kingdom or the rest of Europe. What can you measure with a cup? Salt, milk, flour, sugar, and butter can be measured with a cup.
Unit 29 – Crayons
What are crayons made of? Crayons are made of oiled chalk. Children love to write and draw pictures with crayons. Why do children use crayons very often? Also, there are various colors of crayons. The first box of crayons was made in 1903. Their colors were black, brown, blue, red, purple, orange, yellow, and green.
Unit 30 – Mosaics
A mosaic is a kind of art. It is made of small pieces of materials such as glass, stone, or paper. Mosaics show some images. The most beautiful mosaic can be found in Rome. It was made by Nero and his architects. It covers the walls and ceiling of the Domus Autrea. Do you want to see this world famous mosaic in the future?