The night came quickly, and in the past, the people in Qingshanzhai did not have much entertainment after nightfall, and they could not sleep while lying in bed, so they could only chatter as a family, or look up at the stars and the moon.

Since Fang Nan began to teach students, every night, the students will tell their families some of the things that Shang Nan said in class during the day, which has become a necessary entertainment activity for every student's family.

Compared with these mountain people who don't have much knowledge in Qingshan Village, Fang Nan has a lot of knowledge reserves, and even talking on weekdays can bring out a lot of new things, and a small story may make the villagers spend this time of boredom before going to bed.

In the daytime general knowledge class, Fang Nan talked about the earth, the moon, the sun, the stars, the alternation of day and night, and the rotation of the four seasons, and at night, the students also told these common sense stories to their families.

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

"Is the earth round? No way, the earth we see is flat. ”

"The earth is very big, only limited to the area of our Qingshanzhai, it is indeed flat, the teacher said that people stand by the sea, and there are ships sailing on the sea, we will see the mast of the ship first, and then we can see the whole body of the ship."

"Oh."

There are things that adults can't understand, but they're not as curious as young people, and they're just listening to stories now, and they don't get into why the earth is a ball, which doesn't matter to them.

"The teacher said that the moon, the sun, and the stars are all one ball, very big, because they are far away from the earth, so we look like they are small, but in fact the moon is just smaller than the earth, and the sun is many, much bigger than the earth, and those stars are actually the same sun, but they are farther away from the earth, so they look smaller."

"I know this, your mother's height is a head behind me, and when I look at your mother from a distance, I will feel that your mother is very small, and when I stand with your mother, it is a normal feeling."

"Our teacher also said that the earth has been revolving around the sun, and the earth is constantly rotating on its own, when the side of the earth where we are turns to the north, and there is no sunlight, then we are here at night, and the other side of the earth is day, which is the alternation of day and night, and the rotation of the four seasons......"

Gradually, as the night deepened, the sound of chatting in the cottage became less and less, and only the sound of insects remained.

A new day has arrived.

In the second general studies class, Fang Nan asked the students the same question from yesterday: "Who can say why we don't fall when the land we are on is under the earth?" ”

Generally, when Fang Nan asks questions, the two study committee members answer first, and this time is no exception, Wang Mu, a male study committee member, is the first to stand up and answer:

"Teacher, I think that whether it is a person, a stick, sand, or a stone, there is a weight, and this weight is facing the earth, and if we grab a stone and put it in the air, it will hit the ground, not the sky or left and right."

Being able to become a member of the study committee is really the smartest person in the class, and Wang Mu's answer is very close to the truth.

Newton was smashed by an apple and discovered gravity It doesn't matter if it's true or not, but Newton was indeed the first person to discover gravity, no one discovered gravity for thousands of years before Newton, there are so many people sitting under the apple tree, and Newton is not the only one who was smashed by an apple, why others didn't discover gravity, but Newton discovered gravity.

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

When encountering things, asking questions, and solving problems, there are three steps, and the number of people who go to one step is the most, and the number of people who go to the second step decreases sharply, and Newton is the first person to go through the third step.

Now, Fang Nan asked the students directly, "Why did the apple fall to the ground instead of falling to the sky or some other direction?" The students then proceed directly to the third step and begin to think about solving the problem.

It was difficult to solve this problem completely, and Newton spent more than 20 years coming to a conclusion and then proving it to others, and it was accepted by most people.

Now it is easy for Wang Mu to come up with a similar guess, but it also takes a lot of time to come to a final conclusion and prove his conclusion to others.

After that, Xu Yue'er, Zhou Lei and others stood up 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 spoke: "Wang Mu's answer is very close to the real answer, and other people's answers are more or less correct, and now the teacher will tell everyone the real answer."

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

Because of gravity, we have to stand on the earth, and only when you jump up, you will leave the earth for a short time, but soon it will fall again, and people jump away from the earth, because you also use force when you jump, but your force is not as strong as the earth, so you will eventually fall. ”

Fang Nan's explanation of "force" is relatively simple, the general knowledge class has just begun, Fang Nan will only talk about some simple things, which can be easily understood by students, and the content in the general knowledge class will become complicated when it is the third year.

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

Of course, this is only a preliminary understanding, gravity, gravitational force or something is complicated, and they still need to understand it in depth for the time being.

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

"Before taking the general knowledge class, you also had the experience of picking up stones and wood with force, and when you let go, the stones and wood would fall to the ground. No.

At the end of today's class, the teacher hopes that you can find things that you can't understand in your daily life, and then think about why this happened, and solve this problem by yourself as much as possible, or you can tell the teacher about this problem, and the teacher will choose to answer or not to answer according to the situation......"