Love lasts a lifetime

When He Yu started class, he did not teach any new lessons. Instead, let the students open the textbook and check each other to see if they have done the exercises at the end of the textbook.

Some teachers find it strange that students are asked to do the exercises in the textbook before the new lesson content is taught.

Is there such a teaching method?

Isn't it obvious that He Yu taught the students about the new textbook content before the open class? '

I originally wanted to ask He Yu, why is this?

But this is an open class, so you can't ask questions casually. You can only suppress your doubts temporarily while students check each other.

He Yu randomly checked the exercises performed by two classmates.

He found that a classmate sitting in the back row had already done three of the six exercises and got two of them correct.

He asked everyone to stop.

Let me show you the two questions that this student got right. And praised the student.

This period of time only took three minutes.

According to the teaching regulations, the time required for organizing teaching is neither too much nor too little.

At this moment. Some teachers couldn't hold themselves back, became a little commotion, and whispered to each other.

One teacher whispered,"What do you call an open class?

You teach the students the new content they want to learn in advance.

Are you deliberately checking whether the students have done the exercises they haven't learned in the textbook?""

"Isn't this the teacher who came to listen to the class nonsense?

The teacher did not teach the new content to be learned, so he asked the students to do exercises, and this student got two questions correct.

If not in advance, I have taught this student alone. This student actually got it right, unless it was Hua Luogeng"

"It is obvious that this part of the textbook content was explained to the students in advance?

Isn't this just messing with the teachers who come to listen to the class?

An old teacher was sitting behind the student. He quietly went to take the student's exercise book and take a look. You really did the exercises right!

He wrote down the student's name.

Don't know what the purpose is?

Just wait and see.

He Yu ignored them and whispered to each other.

He secretly knew that they were dissatisfied and did not understand his teaching method.

Regardless of the wind and waves, he stayed on the fishing boat.

He said:"Students!

Let's study and study the content of the new lesson together. What we are going to study today is the formula of the angle between two straight lines.

Before the discussion, let everyone recall how many positions of two straight lines are there?

A student Raise your hands and say:"Teacher, I know!"

"good!

Just answer

"There are three positions. One is parallel, one is coincident, and the other is intersection. There is only one intersection point when intersecting"

"The answer is correct, let me ask you again, what is the relationship between these three positions and the slopes between them?"

"When they are parallel and coincident, the slopes are equal, and when they intersect, they are calculated according to the equations of their respective straight lines."The student replied

"The students asked, was he right?"He Yu asked

"That’s right, very straightforward!"Many students said

"Anyone else have anything to add."He Yu asked

…….

"If there is nothing to add, let’s study together how to calculate the angle when two straight lines intersect.

Before studying, I want to ask; what is the inclination angle of a straight line?"

A few students raised their hands.

He Yu asked a student in the front row to answer.

The student replied:"The inclination angle of a straight line when it is parallel to or coincident with the x-axis is 0.

If the straight line is not parallel to or coincident with the x-axis, it must intersect with the x-axis.

At this time, taking the x-axis as the reference, the angle formed between the positive direction of the x-axis and the upward direction of the straight line is called the inclination angle of the straight line.

The student walked up to the podium and drew a figure on the blackboard.

He also wrote that the value range of the straight line inclination angle α is: 0≤α180

"Great answer!

I think this student not only answered correctly, but also drew beautiful pictures and plotted them very accurately.

The value range of the straight line inclination angle α is clearly stated.

Students must keep in mind that the value range of the straight line inclination angle α is greater than or equal to zero, but can only be less than 180.

And also remember that the angle between the straight line and the positive direction of the x-axis and the upward direction of the straight line is called the inclination angle of the straight line.

This classmate is clearly marked with a red line.

Therefore, the slope of the straight line is calculated according to this regulation.

This is very critical to the calculation of the angle between the two straight lines that we will study in the next step.

Have you remembered it?"

A few teachers who came to listen to the class pointed at the pictures and whispered what they were saying.

He Yu looked at the pictures carefully and felt that there were no mistakes at all, and the drawings were very accurate and beautiful.

He ignored them and continued to teach.

Really; one after another. Don't panic when taking pictures, and ask questions in a precise and precise manner.

It's not a lecture, but a performance by the students.