What is electricity? The idea of electricity is hard to understand because electricity has no shape. Electricity can be visible or invisible, depending on the situation. That is, you can see it sometimes, but cannot see it at other times.

Let’s take up an example of electricity that you can see. When you comb your hair, some of your hair may stand straight up. You may even hear a popping sound. You are seeing and hearing signs of electricity. Another example is lightning. Lightning sometimes comes with thunder, but more often it happens in the sky without making any noise.

Science explains that electricity is a flow of energy and it’s part of nature. This understanding of electricity started with a clever experiment. In 1752, Benjamin Franklin used a kite for an experiment one stormy night in Philadelphia. This is called Franklin’s kite-in-the-thunderstorm experiment. Through this experiment, Franklin discovered that lightning is a type of electricity.

Sound comes through your ears. It may be a human voice, the singing of birds, or music. But what is sound? What happens in your ear when you hear something?

First, let’s think about what sound is. A sound is a vibration and moves in waves. We call such waves “sound waves.” Sound waves are made when something vibrates. Sound waves can move through air, water, and solid materials. Sound waves travel at 343 m/s (meters per second) through the air, but they go faster through water and solid materials. You may wonder why. If you imagine dominos falling one after another, you’ll see why.

Now, let’s look into how we hear. When you hear something, sound waves enter your ear and go through a small tunnel in the ear. These sound waves pass through the tunnel to the small bones in the middle ear. These small bones vibrate. Then, in your inner ear, nerves catch the sound waves and send messages to your brain. Finally, your brain tells you what kind of sound you are hearing.

The first computer weighed almost 24,500 kilograms. Nowadays, a computer that is more powerful than the first computer weighs just a few grams. Once a computer became so light, it was easy to carry in your pocket. Now you may realize that the computer we’re discussing is your smartphone.

Yes, smartphones are new types of computers. They are light and portable. And with a single smartphone, you can make phone calls, send text messages to your friends, search for information on the Internet, and use social networking apps, and more.

You may wonder why we call this new type of phone “smart.” We call a smartphone smart because it is “really clever” and “super-efficient.” You may find the same usage of the word in new words such as “smart TV,” “smart home,” or “smart electric appliances.”

People learn in three different ways: knowledge building, observation, and reflection.

First, learning comes through knowledge building. Typically, this happens at school, or from reading books or doing research on your own. We need to remember that information is different from knowledge. Information comes and goes, and it never stays in your mind. You need to think about information to make it part of your knowledge.

Second, you learn from observation. Young children are good at this type of learning. They learn what is good and what is bad by observing when their mothers and fathers get angry or when their older brothers or sisters are punished.

Third, we learn from our own experience. However, experience does not automatically lead to learning. If you want to learn something from your experience, you have to reflect on it and think about the meaning of that experience in your life.

Wheelchair tennis is one of the major wheelchair sports in the world. It is also an official sport in the Paralympics. Shingo Kunieda is one of the top wheelchair tennis players and has ranked first for many years. He has been in a wheelchair since he was nine years old and started playing wheelchair tennis at 11 years old. Shingo won the doubles title in the Athens Paralympics in 2004 but was not mentally strong enough to win other games. A mental trainer advised him to shout “I’m the strongest!” every day. Following the advice, Shingo had been winning singles titles. But he had no one to defeat anymore so he lost motivation to continue playing tennis. So Shingo challenged himself to get better every day. Shingo announced in 2009 that he would turn professional. He plays to win titles and encourage children to have hopes and dreams like he once did as a boy.

Oxford University professor Robin Dunbar stated in a study that people whose ancestors lived within the Arctic Circle have 20% larger eyeballs compared to those who lived near the equator. Previous studies have shown that the size of one’s eyeballs is associated with the size of the visual part of the brain. The larger the eyeballs, the higher the brain volume. It increases with latitude: people who live in higher places north and south of the equator have larger brain sizes.

Studies published in Biology Letters showed that the biggest brains (about 1,484 millimeters in size) were from Scandinavia whereas the smallest brains (about 1,200 millimeters in size) were in Micronesia. The eye size was also notably larger in Scandinavia, with 27 millimeters and 22 millimeters in Micronesia. Professor Dunbar said, “It’s only within the last 10,000 years or so that modern humans have occupied all latitudes right up to the Arctic Circle.” He concluded that the development may have happened within the last 10,000 years.

Rainforests are jungles that grow near the equator. The equator is the line between the north half and the south half of the earth.

Rainforests cover less than 3% of the Earth’s area, yet rainforests are home to more than half of our planet’s land animals. You may wonder why this is possible. Here is the reason.

In areas around the equator, temperatures are high, and it rains almost every day. These conditions are the best for wild animals. The climate there may be too hot and humid for humans, but it is a good place to live for wild animals. This is true for plants as well. In fact, about half the world’s plants are found in tropical rainforests.

Unfortunately, rainforests are disappearing quickly: an area about the size of 40 football fields disappears every minute. We should do something about it before it’s too late.

There are two purposes of education. One is building up knowledge; the other is maintaining social order.

First, you are educated to build up knowledge for yourself. In order to grow up as a person, you need to gain enough knowledge in various areas of study. You need to know enough about the world, humanity, science, and technology to contribute to the peace and prosperity of the world.

Second, you are educated to maintain social order. Through education, you’ll learn how to work together with other people. We call this “collaboration.” If you learn that collaboration is more efficient than working individually, our society as a whole will develop peacefully.