Unit 1- The Human Body
A person has a head, neck, chest, two arms, and two legs. Also, a human body consists of fat, muscles, and bones. Do you know how many bones there are in your body? There are about 200 bones in a human body. These bones protect our organs, such as the heart and lungs. We need to have a good diet to have a healthy body.
Unit 2- The North Pole
The North Pole is located in the middle of the Arctic Ocean. In winter, the temperature reaches to -49oF. Even in summer, the temperature is around 32oF. During the summer, we can see white nights at the North Pole. Ice at the North Pole is usually 2 or 3 meters thick. However, the North Pole is warmer than the South Pole.
Unit 3- Pine Trees
If people look around, they can easily find pine trees. There are about 115 kinds of pine trees all over the world. People use pine trees for many reasons. In old times, people built houses with pine trees. Now, people use pine-leaf powder for healthy drinks. Also, dried pine trees are good for baseball bats. What a useful tree it is!
Unit 4- Bird Nests
A bird nest is built with a lot of small twigs, grass, and leaves. Some birds that live close to the ocean build their nests with fish bones. Mother birds build a nest to protect eggs and baby birds. It takes a few days to build a complete nest. Did you ever closely look at a bird’s nest? Go out and try it, but be careful. You might get attacked by a mother bird.
Unit 5- Bees
Many people do not like bees. Bees protect themselves and their hives by stinging humans. However, bees do a lot of jobs in nature. Bees make honey, and people can enjoy the sweet honey. Bees move pollen between plants. These flowers produce fruit. If there were no bees, maybe we could not eat fruits.
Unit 6- Body Temperature
Our body temperature is usually 36.5 degrees. Body temperature is usually taken from a person’s forehead, ear or in one’s mouth. When we are sick, our body temperature goes up. A high fever means our bodies are fighting against bacteria or a virus. Sometimes, a high fever is very dangerous. We have to take medicine to lower it.
Unit 7- Fresh Water
Fresh water comes from ponds, lakes, rivers, and streams. People use fresh water for drinking and farming. People can only drink fresh water. People should drink 2 liters of water every day to make their bodies healthy. Believe it or not, 18 percent of the world’s population does not have enough drinking water. Therefore, people should try to protect fresh water on Earth.
Unit 8- Magnets
Magnets are very interesting objects. Each has a positive pole and a negative pole, one for each end. Similar poles push each other away. Different poles pull each other closer. A compass is a kind of magnet, and it is very useful. With a compass, we can easily find where we are.
Unit 9- Elephants
An elephant is one of the biggest animals in the world. Therefore, it eats a lot. An elephant eats 150~200kg a day. It usually eats twice or three times a day. An elephant eats 60~70 tons a year. So, it eats 15 times more food than it weighs a year. It also drinks a lot of water. It drinks 5~7 liters at once.
Unit 10- Skin
Skin fills a lot of important roles in our body. If we didn’t have skin, viruses and bacteria could easily get into our bodies. If that happened, these viruses and bacteria could make many diseases in our bodies. Skin also stores water and blood in our bodies. We cannot live without skin. Therefore, we have to take good care of our skin.
Unit 11- Soil
Soil is necessary for people’s lives. Plants can grow from soil. Soil gives plants a lot of nutrition. Plants can make flowers and fruit with this nutrition. Therefore, soil is very important for us. Soil has different colors. Sometimes, it is brown. Sometimes, it is black. And sometimes, it is even red.
Unit 12- Gorillas
About 99 percent of a gorilla’s DNA is the same as a human’s. Therefore, they are one of the smartest animals. Gorillas live in the forests in Africa. Their height is usually about 5 ft 5~5 ft 9 inches. They weigh about 310~450 lb. Gorillas eat fruit, leaves, and small insects. They also have fingerprints like humans.
Unit 13- Special Family Days
Each family has its own special days like birthdays and anniversaries. When is your birthday? What about your mother’s and father’s?Families get together to celebrate birthdays. Families also get together when they have wedding ceremonies or special days. It is important to remember your family’s special days.
Unit 14- The Home
A home is a place for people to live in. People take a rest at home, and they cook at home. Also, they store many things at home, and they spend a lot of time at home. There are many different kinds of homes. They are apartments, town houses, mobile homes, and single family homes.
Unit 15 – The Government
A government does a lot of things for the people in a country. The government maintains military and police to protect people. The government helps poor people. The government also supports education by building schools. The government does many things to protect nature. Do you know when the first government was created? It was more than 5,000 years ago.
Unit 16 – Continents
There are 6 continents in the world. They are Asia, Africa, North America, South America, Europe, and Australia. Most continents are on the north side of our globe. The biggest continent is Asia. Korea, Japan, and India are parts of Asia. North America has only the U.S.A., Canada, and Mexico.
Unit 17- Customs
Each country or culture has its own customs. Korean and Chinese people celebrate a Lunar New Year holiday. And Korean people respect their ancestors very much. They go to their ancestors’ tombs every year to take care of them. In many Western countries, people throw rice to brides and grooms. Western people think rice is the symbol of wealth, health and happiness.
Unit 18- Healthy Food
What kind of food do you like? Different people like different food. Eating healthy food makes your body healthy. Usually, food with a lot of oil is not healthy. And fried food can cause a lot of diseases. Fast food, such as hamburgers and pizza, is also known for not being healthy. Vegetables, fruit, and whole grains are all healthy food.
Unit 19- Natural Resources
What kind of natural resources can you think of? We can easily think of oil, coal, gold, and iron. These usually come from under the ground. Air, water, and wind are also natural resources. Natural resources are limited. If people use up all the natural resources, there will be no more of them in the future.
Unit 20- The People
“The people” means a large number of men, women, and children in the same country. Therefore, the country protects the people. It provides plenty of public services for the people as well. Different people have different customs and histories. They also have different languages, cultures, and religions.
Unit 21- Christopher Columbus
Christopher Columbus was a very brave sailor and explorer. He was born in Genoa, Italy. He believed the world was round. Columbus tried to find a new way to India. Spain’s queen supported his journey to India. In 1492, he found a new land. But it wasn’t India. It was the American continent. Columbus kept believing it was India until he died in 1506.
Unit 22 – The War
There were a lot of wars in our history. People make wars to get something. In the old days, some countries invaded other countries to expand their lands. During war, a lot of people die, and many buildings are destroyed. Sometimes families are separated. The oldest war in history happened more than 5,000 years ago.
Unit 23 – Slavery
Slavery began a very long time ago. People bought slaves with money. A slave’s life was miserable. Some people treated slaves as animals. Abraham Lincoln, the 16th president of the U.S.A., was against slavery. He fought to make slaves free from their owners. However, believe it or not, 27 million people are still slaves in the world.
Unit 24 – The President
The president is a leader of a country. The president represents his or her country toward other countries. The president serves their country. The president does a lot of different jobs. The president makes laws and leads an army. Who was the first president in history? The first president of a country was George Washington. He became president of America in 1789.
Unit 25 – Addition
Addition is the process of putting numbers together. Addition is one of the simplest things in math. It is very basic in math as well. Everybody knows the plus sign”+.” The plus sign is one of the symbols in math. Plus means “more” in Latin. When was the plus sign first introduced? In 1557, one German mathematician introduced the plus sign for the first time.
Unit 26 – Hexagons
A hexagon is a shape that has six edges and six vertices. In other words, a hexagon has six angles and six straight sides. The angles inside of a regular hexagon add up to 720o. Can you find hexagon shaped objects around you? Honeycombs are hexagons. Some snowflakes are hexagons. Also, turtles’ backs have hexagon shapes.
Unit 27 – The Calculator
A calculator is a device for calculations in math. It is not a computer, and it is usually small, digital, and inexpensive. Many students use calculators for their school work. The first pocket-sized calculator appeared in about 1970 around the world. Because it was powered by batteries, it was portable, handy, and very convenient. However, it was very expensive. It cost almost 400 U.S. dollars.
Unit 28 – Inches
An inch is a unit of length. 12 inches are the same as a foot, and 36 inches are the same as a yard. How much is one inch in millimeters? One inch is equal to 25.4 millimeters. The inch is used only in a few countries such as the United States, Canada, and the United Kingdom. All other countries use the meter instead.
Unit 29 – Canvas
Canvas is used for oil painting. It is made with various kinds of fabrics, such as cotton, linen, and polyester. Canvas is not only used for painting but also for making tents, sails, umbrellas, and shoes. The first canvas was introduced around 1410 in Berlin. But it didn’t become very popular in Europe until the 17th century.
Unit 30 – Crafts
Crafts are activities and hobbies for making something. People do crafts with their hands and skill/ a lot of crafts need skill, speed, and patience. A lot of schools teach basic craft skills to students. There are many different types of craft, such as card making, knitting, jewelry making, pottery, doll making, egg decorating, and so on.