Dear judges and teachers: Hello everyone! I am candidate No. 6 in the interview for primary school mathematics teachers, and the topic of my trial lecture today is "Position and Direction (2)", so I will start my trial lecture below.
1. Create scenarios and introduce new lessons.
Teacher: Hello students! Have a seat! Teacher: Students, have you ever seen a typhoon?
Teacher: Today, the teacher has brought you a report on typhoons, please look at the big screen! At present, the center of the typhoon is located 30 degrees south-east of City A, 600 km away from City A, and is moving in a straight line towards City A at a speed of 20 km/h.
Teacher: Observe what kind of mathematical information can you find out from it?
Teacher: Okay! Everyone found that the center of the typhoon was 600 km away from City A and 30 km south-east of City A. The travel speed is 20 km/h. Teacher: How does a typhoon move? Please get up and talk about this boy by the window!
Teacher: Well, everyone is very good at observing! It can be seen that the typhoon is moving in a straight line from the ocean towards City A. Now where is the exact location of the typhoon? How do you put it there?
Teacher: The teacher saw that everyone had puzzled expressions on their faces! We will know through today's Xi. Today we will learn about Xi Position and Direction (2).
2. Teacher-student cooperation, new knowledge.
Teacher: First of all, please think about it: On the map, it is generally stipulated that the four directions of east, west, north and south are in **?
Teacher: Oh, you remember what you have learned so firmly! I still remember that on the map, it is generally stated that it is up to the north, down to the south, left to the west, and right to the east.
Teacher: However, now that we want to observe the location of the typhoon, what is the most appropriate observation point for **?
Teacher: Well, some classmates said that City A. You're smart! Look at the big screen! Since it is to observe the typhoon, the four directions of east, west, south and north are determined with City A as the observation point.
Teacher: But what does 30° mean by south-east? Let's talk to your table mates first!
Teacher: Okay! The teacher's voice is getting quieter and quieter when he hears the exchange, so please get up and talk about this girl with glasses! Teacher: Well, this student mentioned the angle of 30°. Yes, 30° south-east means that the center of the typhoon is relative to the direction where city A is located, that is, the angle between the center of the typhoon and city A and the direction due east is 30°, that is, the east is 30° south.
Teacher: If there is only 30° south-east, can we determine the specific location of the typhoon center?
Teacher: Oh, when I saw that everyone shook their heads, they all felt that they couldn't. It is true that we only know the general direction of the typhoon, but we do not know how far the typhoon is from City A. To determine the exact location of the center of a typhoon, two conditions must be known, namely, the direction in which the object is located and the distance of the object from the observation point in that direction. So now can you be sure that the center of the typhoon is in **?
Teacher: Well, that is, the center of the typhoon is 30 degrees southward due east, and it is 600 kilometers away from City A.
Now the teacher has also marked the direction of the typhoon on a large screen.
Teacher: Calculate how many hours after the typhoon arrives in the city? Do the math on your worksheets! Teacher: Okay, everyone is done, tell me what you think!
Teacher: That's good! He used the distance of the typhoon's center from city A by 600 kilometers, and subtracted the speed of the typhoon moving at a speed of 20 kilometers per hour, to get the time for the typhoon to arrive in city A. The equation is 600 20 = 30 (hours), so the typhoon will reach City A in about 30 hours.
Teacher: Now please take a look at the big screen again, this is the weather forecast for a certain day**, let's take a look!
Division: City B is located 30° west-north of City A, 200 km away from City A, and is directly north of City A, 300 km away from City A. Can you mark the location of City B and City C in the direction board we just drawn? Draw yourselves on this picture in the book! Let's go!
The distance of the object from the observation point in this direction. So now can you be sure that the center of the typhoon is in **?
Teacher: Well, that is, the center of the typhoon is 30 degrees southward due east, and it is 600 kilometers away from City A.
Now the teacher has also marked the direction of the typhoon on a large screen.
Teacher: Calculate how many hours after the typhoon arrives in City A? Do the math on your worksheets! Teacher: Okay, everyone is done, tell me what you think!
Teacher: That's good! He used the distance of the typhoon's center from city A by 600 kilometers, and subtracted the speed of the typhoon moving at a speed of 20 kilometers per hour, to get the time for the typhoon to arrive in city A. The equation is 600 20 = 30 (hours), so the typhoon will reach City A in about 30 hours.
Teacher: Now please take a look at the big screen again, this is the weather forecast for a certain day**, let's take a look!
Division: City B is located 30° west-north of City A, 200 km away from City A, and is directly north of City A, 300 km away from City A. Can you mark the location of City B and City C in the direction board we just drawn? Draw yourselves on this picture in the book! Let's go!
Teacher: You've finished drawing, right? The teacher also showed the picture you just drew on the big screen, check if they drew it correctly? How did you draw it? Talk to each other within your group.
Teacher: Okay! It's time! Representatives of Group 3 are invited to stand up and have a talk!
Teacher: Well, he mentioned using a protractor to measure. Yes, first determine the direction, the center point of the protractor coincides with city A, the 0 scale line of the protractor coincides with the direction of due north, and measure 30° to the west, so that the protractor is used to measure 30° to the west of north; Then the distance is expressed, 1cm is used to represent 100km, city B is 200km away from city A, and it is 2cm on the map.
Teacher: Yes, it's the same method, first find the direction due north of city A, and then show the distance, 1 cm means 100 km, and city C is 300 km away from city A, which is 3 cm on the map.
Teacher: To sum up, how do you determine the location of a place?
Teacher: Well, that's right! There are two steps, one determines the direction and the other represents the distance.
3. Consolidate Xi.
Teacher: It seems that everyone has almost mastered it! The teacher also wants to test everyone's mastery! Fill in the directions and distances in the image below!
Teacher: It's time! Who will be a little teacher to answer everyone's questions? Please bring the results of your work to the table.
Teacher: Well, he filled in the specific directions and distances of the four places in Xiao Ming's house. Very clearly expressed! Do you think the same way? It seems that everyone's accuracy rate is very high!
Fourth, summarize and review.
Teacher: What have you gained from learning Xi this lesson? Tell us about the bespectacled girl. Teacher: She said that she learned how to determine the location of a place.
Division: What a good boy who can Xi! So what is the method of determining the location? Please.
Teacher: Yes, first determine the direction of a place, and then indicate the distance of the place from the observation point.
Teacher: It seems that everyone has gained a lot from this class! Seeing that everyone is getting better and better at learning Xi, the teacher is really happy for everyone!