The night soon came. In the past, people in Qingshan Village did not have much entertainment activities after nightfall. They lay in bed and couldn't sleep. They could only chat with each other, or look up at the stars and the moon.

Since Fang Nan started teaching students, every night, students will tell their families some of the things Fang Nan said in the classroom during the day, which has become a must-have entertainment for every student's family. If some families do not have students, they will gather in families with good relationships with students.

Compared with these mountain villagers who have little knowledge in Qingshanzhai, Fang Nan has a lot of knowledge reserves for two lifetimes, and even can bring out a lot of new things when talking on weekdays. A small story may allow the villagers to spend the bored period before going to bed.

In the daytime common sense class, Fang Nan talked about the earth, the moon, the sun, the stars, the alternation of day and night, and the four seasons rotated. At night, students also used these common sense as stories to their families.

"Our teacher said that the earth is a ball, a ball is like a round fruit."

"Is the earth round? It's impossible, the earth we see is flat."

"The earth is very big and limited to the area of ​​Qingshanzhai. It is indeed flat. The teacher said that people stand by the sea and ships sailing on the sea. We will first see the mast of the ship, and slowly we can see the whole body of the ship."

"oh."

Some things are unresolved by adults, but their curiosity is not as strong as young people. They are listening to stories now and will not dig deep into why the earth is a ball, which is not important to them.

"The teacher said that the moon, sun, and stars are all a ball, which is very big. Because it is far from the earth, we look like they are very small. In fact, the moon is just smaller than the earth, and the sun is much bigger than the earth. Those stars are actually suns, but they are far from the earth, so they look smaller."

"I know this. Your mother is one head different from me. When you look at your mother from a distance, you will feel that your mother is very small. It is normal when I stand with your mother."

"Our teacher also said that the earth has been circling around the sun, and the earth is also constantly rotating itself. When the earth where we are turned to the north, without sunlight, then we are night here, and the earth on the other side of the earth is daytime, which is the alternation of day and night, and the rotation of four seasons..."

Gradually, it was late at night, and the chatting sounds in Qingshan Village became less and less, leaving only the sound of insects.

A new day is coming.

In the second common sense class, Fang Nan asked the students the question yesterday: "Who can tell me why we don't fall when the earth we are in is under the earth?"

Generally, when Fang Nan asked questions, two study committee members answered first. This time was no exception. Wang Mu, a male study committee member, was the first to stand up and answer:

"Teacher, I think no matter whether it is a human, a stick, a sand or a stone, there is a weight. This weight is facing the earth. If we grab a stone and put it in mid-air, it will hit the ground, not hit the sky or the left and right."

Being able to become a study committee member is indeed the smartest people in the class. Wang Mu's answer is very close to the truth.

It doesn't matter if Newton was smashed by an apple and found that gravity was true or false, but Newton was indeed the first person to discover gravity. No one discovered gravity for thousands of years before Newton. There were so many people sitting under the apple tree, and Newton was not the only one who was smashed by an apple. Why didn't others discover gravity? It was Newton who discovered gravity.

Simply put, Newton noticed the "apple fell to the ground" and asked the question, and the next step was to solve this problem.

When encountering things, asking questions and solving problems, there are three steps. The most people who go to one step, and the fewer people who go to the second step, and Newton is the first person to complete the third step.

Now Fang Nan directly asked the students the question "Why did the apple fall to the ground instead of the sky or other directions?", and the students went directly to the third step and began to think about solving this problem.

It was difficult to completely solve this problem. Newton also spent more than 20 years to draw a conclusion and prove it to others, and it was recognized by most people.

It is easy for Wang Mu to make a similar guess now, but it also takes a lot of time to draw a final conclusion and prove his own conclusion to others.

Afterwards, Xu Yueer, Zhou Lei and others stood up one after another to answer Fang Nan's questions, and their words were all related to the weight of the object.

After the students finished answering, Fang Nan said, "Wang Mu's answer is very close to the real answer, and the other people's answers are more or less correct. Now the teacher will tell you the real answer.

I pick up a mud ball or something, and I need to use force to pick it up. The term "force" is very important because the earth or the earth under our feet exerts a "force" on everything on the ground. This "force" is the "weight" in your air. The correct way is "gravity".

Because of the existence of gravity, we humans must stand on the earth. Only when you jump up will you leave the earth in a short time, but it will soon fall down. People jump away from the earth because you also exert force when you jump, but your force is not as strong as the earth, so you will eventually fall down."

Fang Nan's explanation of "power" is relatively simple. Common sense class has just begun. Fang Nan can only talk about some simple things that can make students understand easily. The content of common sense class will become more complicated until the third academic year.

Fang Nan said so simply that the students quickly understood the concept of "gravity", which is also a conclusion. Compared with the conclusion that "the earth is a ball" that cannot be proved in a short period of time, "gravity" is more intuitive. Students can understand "gravity" after careful observation and analysis.

Of course, this is just a preliminary understanding. Gravity, gravity, etc. become more complicated, and they are still "primary school students". They do not need to have an in-depth understanding for the time being.

After talking about "gravity", only half of the time passed. In the rest of the time, Fang Nan did not talk about new common sense. Instead, he used the problem of "gravity" to tell students a truth: be good at discovering and be diligent in thinking!

"Before taking common sense class, you have also personally experienced the fact that when you pick up stones and wood with force, when you let go, the stones and wood will hit the ground. At that time, you thought about the stones and why wood hit the ground? No.

At the end of today's class, the teacher hopes that you can find things that you cannot understand in your daily life, and then think about why this happens, solve this problem as much as possible, and also tell the teacher about this problem. The teacher will choose to answer or not answer it according to the situation..."
Chapter completed!