In recent years, although Shi Dizheng has been taking the high school entrance examination, the proportion of scores is not high after all.

Therefore, in the junior high schools of provinces, cities and counties, there has always been a clear difference between the subjects of history, geography and politics and mathematics, physics and chemistry in terms of teaching focus.

In this regard, Beishan Township Middle School is even more so.

Take teachers as an example, the teachers who teach history and geography in schools are generally either of a certain age, or too low-level, or too serious at work, etc......

In short, the teachers who teach history and geography in their school are definitely the most inferior teachers in the school in terms of teaching, and some are even inferior to the old Feng Tou'er who retired before.

Of course, this is not to say how well the teachers who teach other subjects, after all, the situation of Beishan Township Middle School is here, and if you want to say it, it is just a big man.

In fact, their school is not without good teachers.

For example, Tang Wan before;

For example, Ms. Zhao, who is now teaching mathematics in the first, second and third years of junior high school;

For example, the current homeroom teacher of the second and fourth classes of junior high school, and Mr. Wu, who teaches physics in the second and fourth classes of junior high school and the fifth class;

For example, Wang Qiang, who is now teaching Zhang Dongming and his third, fifth and fourth classes of English......

Relatively speaking, these are still very good teachers, teaching is serious and responsible, the key is that the level is okay, but there are only three or four such teachers in the whole school.

Just like Zhang Dongming's class, except for English, the level of teachers in other subjects is too average, but if he can get by a little, he won't think about going into battle by himself.

In the morning, Zhang Dongming greeted the two male teachers who taught politics and geography in their class.

It seems that Gong Liguo communicates very well, or these two teachers themselves are happy to teach less, in short, there is no nonsense, they only came to the sentence "I know" and didn't say more.

As for the old Yang Ertou who called them class history, he hasn't come to work in the past few days, and I heard that there seems to be something wrong with his body, and he has to raise him for a while.

As for the teacher who taught them mathematics, physics and chemistry, anyway, Gong Liguo had already said that Zhang Dongming didn't say hello, they talked about their class, and he talked about his workbook, which didn't affect each other for the time being.

However, he still went to find the teachers of these three subjects, mainly to understand the current teaching progress.

Language lessons.

After more than a month of open teaching and various indirect guidance, the content of Zhang Dongming's lectures has basically returned to the textbook.

Of course, it's just basic.

Unless there is some necessary basic knowledge, Zhang Dongming will still talk and nag with the students.

Zhang Dongming has always felt that especially in middle school Chinese, students often learn not those rigid textbook knowledge, but thoughts, insights, and even life, so he prefers to talk more in this regard.

The bell rang for the end of class.

Zhang Dongming returned to the podium: "I'll tell you something." ”

These days, in terms of guiding students to learn, although Zhang Dongming has only received the effect of Ma Hongxu and Qi Lili, he has done his best for every student in the class.

And the rest of the students, although they still don't study at all, it doesn't mean that they don't realize Zhang Dongming's goodness, just like the classroom discipline of class five today, at least those students don't affect others' learning and don't affect the teacher's lectures.

It's the same now, when the bell rang for the end of class, a few students had already gotten out and were ready to go out, but when they heard the head teacher say that something was wrong, they all took the initiative to sit back.

Zhang Dongming looked at the students and said slowly: "From today onwards, the history and geography class of our class may not be taken for the time being, and the exercises of mathematics, physics and chemistry will be changed to me." ”

Although Zhang Dongming had already told Zhao Xiaoli, Bai Dongsheng, Wu Chang, Bai Juan, Ma Hongxu, and Qi Lili, the six students in the class, about this, because he asked these students not to tell others first, the other students in the class didn't know about it yet.

Then hearing Zhang Dongming's words, the students' reactions were divided into two waves.

One wave is Zhao Xiaoli Bai Dongsheng and the six of them are learning, since the head teacher told them about it a few days ago, they have been waiting, and today is finally going to start, they are all very happy and looking forward to it.

The other wave is those in the class who don't learn, because they don't study at all, they don't care about it at all, but they are all very curious, curious about what the class teacher will be like when he talks about mathematics, physics and chemistry, and whether it will be as interesting as teaching Chinese.

The students' reactions were also expected, Zhang Dongming smiled and didn't say much: "Let's get out of class, let's go to the next class on math problems." ”

Ten minutes after class, Zhang Dongming went back to the office and drank a glass of water.

Wang Qiang and others were all in the office, but no one asked Zhang Dongming about it, after all, it had nothing to do with them, they might not know it yet, they might not know it, they might not know it, they might not have said it in front of him.

The class bell rang, and Zhang Dongming came to the class with a math study book.

Now that their class has just finished teaching "Practical Application of One-Dimensional Quadratic Equations", Zhang Dongming plans to lead the students to do the workbook from here.

The main thing is to follow the progress of teaching, and the front one is slightly behind, but it's okay, and the impact is not great.

Zhang Dongming has basically read or done all the questions in the exercise book, and it is definitely unrealistic to talk about each of them in so many questions, he mainly picks some types of questions or questions with comprehensive knowledge points.

Zhang Dongming flipped through the exercise book: "Turn to page 14 and take a look at question 13." ”

Although the workbook was distributed to every student in the class, except for Zhao Xiaoli and Bai Dongsheng, the other students did not bring them.

In fact, these students not only did not bring their math workbooks, but they also did not bring all the workbooks, not only did they not bring all the workbooks, but their schoolbags were basically empty.

In the past, when Tang Wan was there, these students would put an English book in their schoolbags, but now they have all changed to Chinese, and then they may also bring an exercise book or something, and then they will bring a pen or oil pen.

This is the schoolbag that these students carry to school day after day, and after eight classes a day, they basically have a language book on their desks or nothing at all.

It's usually nothing, but now it's the class teacher's class after all, and these students are a little embarrassed, one by one or hehe laughed twice, or turned through the language books in pain.

Zhao Xiaoli and Bai Dongsheng studied a few times, and they all looked at the exercise book carefully.

[One person contracted the flu, and after two rounds of infection, a total of 121 people contracted the flu, and in each round of infection, an average of one person infected several people?]

The math teacher just finished talking about "Practical Application of One-Dimensional Quadratic Equations" yesterday, and they haven't done this in their workbook yet, and then this problem seems to be quite difficult, and I don't have any ideas for a while.

For the first lecture, Zhang Dongming didn't know a lot about the problem, and asked: "Has Mr. Sun told you that when we solve the application problems of one-dimensional quadratic equations, we generally set what we ask as x." ”

"Tell me. ”

"Well, I did. ”

Zhao Xiaoli and Bai Dongsheng hadn't spoken yet, Ma Hongxu and Qi Lili spoke first.

Zhang Dongming smiled and nodded, although there are many cases that are not like this, but it has nothing to do with the current question: "Okay, then this question, let's set the question to x."

At the beginning of the question, a person had the flu, and after two rounds of infection, a total of 121 people had the flu, and now we set the number of people infected by a person to x, so when the first round of infection ends, the total number of people who have the flu should be the sum of the number of people infected by him and the person himself?"

Zhao Xiaoli, Bai Dongsheng and Ma Hongxu both nodded directly, Wu Chang, Baijuan and Qi Lili both reacted, and then nodded as well.

Zhang Dongming looked at Qi Lili: "After the first round of infection, how many people have changed to the flu?"

Qi Lili said: "1+x people. ”

Zhang Dongming smiled and nodded, asked Qi Lili to sit down, and said slowly: "Yes, after the first round of infection, a total of 1+x people have the flu. And then in the second round of infection, each of these people will be infected to x people, so think about it, in the second round, how many people will be infected?"

Zhang Dongming paid attention to the expressions of each student, and finally looked at Ma Hongxu.

Ma Hongxu stood up: "X (1+X) people." ”

Zhang Dongming also smiled and nodded, and asked Ma Hongxu to sit down: "These x (1+x) people are the number of people who have increased in the second round, so in our current question, a total of 121 people have suffered from the flu after two rounds of infection, and these 121 people should be the total number, right?" ”

The students nodded.

Zhang Dongming half-turned around and said slowly while writing on the blackboard: "In the question, there was 1 person who had the flu at the beginning, and after the first round, it was 1+x people, that is, x people were added, and after the second round, x (1+x) people were added, and the 121 people given in the question should be the number of people at the beginning, plus the increase in the first round, plus the increase in the second round, the sum of these three parts?"

The students all nodded.

Zhang Dongming looked at Bai Dongsheng: "Then how should we list this equation?"

Bai Dongsheng stood up and didn't think about it: "1+x+x(1+x)=121." ”

In the huge classroom, there were only six students listening to the class, and it was clear at a glance, Zhang Dongming had been paying attention to their reactions, and made sure that they all understood, Zhang Dongming finally asked Bai Juan to go to the blackboard to turn the equation into a general form: x?+2x-120=0

Bai Juan returned to her seat, and Zhang Dongming asked: "What method can be used to solve the general form of a one-dimensional quadratic equation, has Mr. Sun talked about it?"

Waited a while.

Only Zhao Xiaoli said: "Matching method, formula method, and factorization method." ”

Zhang Dongming nodded, it seems that other students are not very familiar with this piece, and it is not something that can be finished in one sentence or two, Zhang Dongming thought about picking a class one day to carefully explain these three methods.

Zhang Dongming asked: "Cross multiplication, Mr. Sun should have talked about it." ”

This time the students all nodded.

Zhang Dongming looked at the students, and finally looked at Wu Chang: "Then what should this equation be factored into?"

Wu Chang stood up and thought for a while: "(x+12)(x-10)=0." ”

Zhang Dongming also smiled and nodded, and asked Wu Chang to sit down: "The product of the two factors is zero, either x+12=0, or x-10=0, so we can solve X1=10, X2=-12."

For the two roots of this unary quadratic equation, because x in this problem represents the number of people, it is obvious that -12 does not fit the topic, because the number of people cannot be negative, so x can only take 10, so on average, no one person will infect 10 people. ”

Zhang Dongming had just finished speaking, and his mobile phone rang.

I originally wanted to turn it off, but when I took it out and took a look, Tang Wan called.

Since calling back to the county, Tang Wan has been sending text messages to him, and he has written a letter at the beginning of school, and he and Tang Wan have not been in contact for a while.

Zhang Dongming came out of the classroom and answered the phone: "Hey......"