3. Start with the wall chart

The two sat down on the sofa, and Teacher Wen still nagged and said, "Principal Qian, you look at the clock too preciously, I just want to open the back cover to see the internal structure, you don't let you see it, it's really not interesting!"

Principal Qian sat there with great dignity, and he said, "You don't have to look at the big clock, just listen to what I say to you." Pen × fun × Pavilion www. ｂｉｑｕｇｅ。 ｉｎｆｏ”

Teacher Wen said: "What you said is too simple, I want to lead the students to disassemble and assemble the clock, just listen to what you say." ”

"What's the use? I won't tell you how the clock works, you probably don't know what the hands of the clock are used to turn in circles!" Principal Qian said.

Teacher Wen Huo Di stood up from the sofa, and he said, "I'm afraid you underestimate me too much!" Principal Qian hurriedly said: "It's not that I underestimate you, it's that you sometimes do your work too badly." ”

Teacher Wen approached Principal Qian and said, "Old principal, let's not say anything else, let's just talk about the power of the watch and the watch hand to turn in circles." ”

Principal Qian saw that Wen Jinyong was chasing after him, so he had to say slowly: "Okay, then you can tell me how this watch hand goes?"

Wen Jinyong raised his head at this time and walked in front of Principal Qian, and said in a ven manner: "At present, there are three sources of power for clocks, the first is your big clock, which is powered by the gravity of the falling heavy objects as energy to drive the watch hands to move.

The second is the horseshoe watch you mentioned, which is powered by the energy released by the return to deformation after the spring spring is wound up to drive the watch hand to rotate.

The third type is the electronic clock, which uses the battery to form an alternating current through the electronic circuit, which generates an inductance through the coil to induce the electromagnet to drive the watch hand to rotate---------。

When Wen Jinyong said this, Principal Qian waved his hand and interrupted him and said, "Okay, don't talk about it, it seems that you know a little bit about clocks." ”

Wen Jinyong had to say modestly on the surface: "I still have to learn more about clocks and watches in the future." Principal Qian stood up, he took Wen Jinyong's hand and pulled him to the boss's desk, he stretched out his right hand and took out a very old horseshoe watch from the desk table of the boss's desk, and he said to Wen Jinyong: "This is the horseshoe watch I prepared for you, it is very rich in content, you take it home and take it apart to study and study it." ”

After he finished speaking, he handed over the horseshoe watch to Wen Jinyong and wanted to send him home, Wen Jinyong saw it in his eyes, and thought in his heart, he followed Principal Qian to the big clock at the door and said, "Old principal, I still want to take your big clock apart and take a look?"

Principal Qian waved his hand and said, "How can you be like a child, can you dismantle this big bell if you want to?" After the principal finished speaking, he looked at Wen Jinyong with both eyes and his face was extremely ugly.

Wen Jinyong knew that he was not interesting, so he walked out of the door with a horseshoe watch in his hand and went downstairs to go home. After hearing that Jinyong left, Principal Qian felt a lot more relaxed, and he said in his mouth, "But I sent away a naughty ghost." ”

Besides, Wen Jinyong disassembled the horseshoe table at home and studied it for a day, and in the evening wrote an internship report on disassembling the horseshoe table as the basis for the lecture, and wrote the main content of the report into the lesson plan, and prepared the content of the lecture for the next day.

In the first week, the workmanship practice class of elementary school students started, and Wen Jinyong walked up to the podium with clocks and handouts and lesson plans in hand, and after a burst of greetings of "Hello teacher!" and "Hello students!".

Teacher Wen began to lecture, he first put the clock on the lecture table, and then he hung a few wall charts of clocks on the blackboard.

He turned to the lecture and said, "The workmanship practice class we are going to take starts with disassembling the clock. Teacher Wen reached out and picked up the horseshoe watch on the table, and pointed to the clock with a finger of his other hand and said, "Although the clock you see is not large, if we take it apart, you will see that its internal structure contains part of the introduction to mechanical principles." ”

When he said this, he put down the watch in his hand, reached out with his right hand, picked up the whip, turned around and pointed to the wall chart on the blackboard, and said to the elementary school students: "Let's start with the wall chart to have a perceptual understanding of the internal structure of the clock--------。 ”