1. Problem introduction.
Teacher: Class!Hello students, please be seated!
Teacher: Looking at the big screen, the students of Hope Primary School have moved into the new classroom, what is in the new classroom?
Teacher: Everyone has said so much!There was a flag, there was a blackboard, and there were new desks and chairs, which was nice and as beautiful as our classrooms!
Teacher: However, the teacher wants to know which of these objects is bigger and which is smaller, so what should we do?
Teacher: Here are two rectangular cards of different sizes, pink and green
Teacher: Yes, we can compare their sizes together, and then let's go into today's class.
Second, ** new knowledge.
Teacher: Please look at the big screen, the blackboard and the national flag, which one is bigger?Please observe it!
Teacher: You read it most carefully, you must have found it!
Teacher: He said that the blackboard was big, and his answer was so loud!
Teacher: Through observation, we found that the blackboard is larger than the national flag. Here, the size of the blackboard surface is the area of the blackboard surface, and the size of the national flag surface is the area of the national flag.
Teacher: Can you try to tell us about the area of the surface of other objects around you?The boy who raised his hand the fastest!
Teacher: He touched the desk and said that the size of the surface of the desk is the area of the desk. The expression is very clear!
Teacher: You held up your math textbook and wanted to say something?
Teacher: She said that the size of a math book is the area of a math book.
Teacher: The teacher understands that she is talking about the size of the cover, and we should say that the size of the cover of the math book is the area of the cover of the math book.
Teacher: Students are really good at observation!From so many examples, we can say that the size of a face of an object is the area of that face.
Teacher: Now that you know what an area is, will you compare the area of two figures?
Teacher: Next, let's look at the second game: blue rectangle or pink rectangle, which area is larger?
Teacher: The teacher heard some students say that the blue rectangle is big, and some students say that the pink rectangle is big. Can we see it directly with our eyes?So how do you compare?
Teacher: The student who raised his hand the fastest said that he couldn't see it with his eyes, so he could put the two figures together and compare them.
Teacher: I'll really think of a way!Let's try it together. Two figures overlapping each other, who is bigger?
Teacher: Oh, I still can't see it. Yes, their length and width are not the same, there is no way to compare, what can I do?
Teacher: Don't worry, the teacher has prepared small circles, triangles, and squares of paper for everyone, and you can choose a figure as a unit to spread out the measurements, and then compare!Let's start the group activities!
Teacher: Seeing that everyone is already sitting upright, which group will show it first?Okay, 1 set!
Teacher: They put together two rectangles with some small round pieces of paper, the pink rectangle needs 10 round pieces of paper to put together, and the blue rectangle needs 12 round pieces of paper, so the blue rectangle is bigger!Teacher: They are neat and beautiful, and they are praisedTeacher: Are there any different methods?How did the 2 groups do it?
Teacher: They use small triangles to put together, the pink rectangle needs 18 small triangles, the blue rectangle needs 21 small triangles, and the blue rectangle is large.
Teacher: That's really good, and I got the same answer!
Teacher: However, in these two methods, there are gaps that are not filled, and we are comparing the parts of small figures
Teacher: You usually have the most ideas, you can tell me!
Teacher: He said that these gaps are not easy to measure, so they can't be added
Teacher: Okay, show me what your group has done!
Teacher: Use small squares to spell pink rectangles, exactly 10 of them are spelled together, and there are no gaps, and blue rectangles need 12 small squares, and there are no gaps, so the blue rectangle is big!
Teacher: How are their measurement methods?I couldn't help but applaud!Teacher: So, what kind of figure is the most appropriate unit of area?
Teacher: Yes, it is most appropriate to use a small square as an area unit, because there is no gap in what can be spelled
Teacher: Actually, mathematicians use squares to define units of areaDivision: The commonly used units of area are square centimeters, square decimeters, and square meters, which can be expressed by c, d, and . Do you know how big 1 square centimeter, 1 square decimeter, and 1 square meter are?
Teacher: The area of a square with a side length of 1 cm is 1 square centimeter, in fact, the area of our fingernails is close to 1 square centimeter
Teacher: The area of a square with a side length of 1 decimeter is 1 square decimeter, follow the teacher to find the 1 decimeter on the ruler, and then use the index finger and thumb of both hands to draw this comparison, 1 square decimeter is so big!
Teacher: The area of a square with a side length of 1 meter is 1 square meter, and each team finds a square cardboard with a side length of 1 meter, touches it with your hands, and looks at it with your eyes, how big is 1 square meter!
Teacher: After the activities just now, I believe you already know how big 1 square centimeter, 1 square decimeter, and 1 square meter is!Next, the teacher is going to test you!
3. Consolidate the application.
Teacher: Which of the three graphics on the big screen has the largest area?Which area is the smallest?
Teacher: Think about it for yourself and count it!
Teacher: Seeing your confident appearance, tell me your answer!
Teacher: He said that the first figure is composed of 8 small squares, the second is 10 small squares, and the third is composed of 9 small squares, so the first one has the smallest area and the second one has the largest area
Teacher: But is each small square the same size?Well, it was discovered by everyone, and each small square represents 1 square centimeter.
Teacher: Then can we know what the area of each figure is?Teacher: Speak in unison!8 square centimeters, 10 square centimeters, 9 square centimeters!Or the first shape has the smallest area, and the second one has the largest area!Teacher: The game was successfully completed, everyone did a great job, and applause is given to yourself!
Fourth, summarize the experience, reflect on the improvement.
Teacher: Let's go into the sharing moment together, and the class will talk about it on your behalf!Teacher: She knows that the size of the desk surface is the area of the desk, and the size of the blackboard surface is the area of the blackboard.
Teacher: Yes, the size of a certain surface of an object is the area of that surface!
Sheng: It is more appropriate to use a square as an area unit, and I also learned Xi area unit.
square centimeters, square decimeters, and square meters. Teacher: You've gained so much!
Teacher: How big is 1 square centimeter?Well, they stretched out their fingers, which were so large in the area of fingernails.
Teacher: We also used a ruler and finger ratio to draw 1 square decimeter, and finally felt a big 1 square meter together
5. After-school homework, expansion and extension.
Teacher: At this point, the pleasant math journey is coming to an end, I believe that you will be able to complete the problems after class, and we will compete with others to do better in the next class!
Teacher: Share what you have learned today with your parents. Teacher: This class is over!
Sixth, the design of the board book.