Reflection on the teaching of rectangular perimeter

Part 1: Reflection on the Teaching of Rectangular Circumference

First, the formation of knowledge should not be given, but should be obtained by inquiry. In the past, this content seems to be to tell the students the formula first, and then guide the students to calculate the perimeter of the rectangle using the formula. Students are now encouraged to explore knowledge on their own. If the students are forced to memorize the formula, then the students learn the knowledge of death, and their thinking is always imprisoned under the teacher's explanation.
The second is to advocate the diversification of algorithms more suitable for the students' reality. For these third-grade primary school students, is it not a more intuitive and understandable formula for the rectangular circumference of the student's own = length + length + width + width? Since some students do not have formulas in their hearts, teachers cannot impose some rigid and abstract mathematical knowledge on them. As long as their algorithms are justified, teachers should encourage them. The new curriculum reform advocates solving problems in different ways. The reason is very obvious. If students can sum up the best and practical calculation methods that are suitable for them, that is the most useful method.

Part 2: Reflection on the Teaching of Rectangular Circumference

In this lesson, throughout the teaching process, students are actively involved in learning, learning solid, flexible, and fulfilling, and have achieved good teaching results. In the process of independent learning, students develop their ability to explore and practice. I think that the following aspects are more successful in the teaching process: First, create a democratic and harmonious teaching atmosphere. I believe that democratic, equal and harmonious teaching should be pursued and strived to be achieved as a teaching goal. Respect the student's personality in the classroom, understand the students' thinking, allow them to have different opinions, encourage them to ask questions, express opinions, and help to supplement other people's incomplete narratives. Realize the interaction between teachers and students, between students and students. Secondly, carefully designed the pre-class paving, breaking through the difficulties. According to the characteristics of the third-year students' thinking development, the spatial imagination is limited, and the understanding of the rectangular formula may be difficult. I designed the topic of finding rectangular objects before class, so that students can understand the characteristics of rectangles in the process of solving problems in various ways. After mastering this feature, when students encounter the calculation of rectangular perimeter, there is a part of cleverness. Students will use the ×2, through the contact comparison, students can easily understand the formula of the rectangular perimeter. This class is also close to the students' actual life in the design of each teaching session and practice. For example, frame the photos, give fences to the vegetable fields, etc., let the students feel that there is mathematics everywhere in life, understand the usefulness of learning the perimeter of the rectangle, and apply the learning to solve practical problems.

Part 3: Reflection on the Teaching of Rectangular Circumference

"The circumference of the rectangle" This is the content of the first public class when I first entered the school. The scene when I first went to this content was blurred in my mind, but after the class, Ming Shu commented a sentence. "You have the same math class as a language class." I was impressed. The class at that time should make people feel very young. Although every step of the Master carefully guides me, there are still many places in their own practice that are not sure. The open class can only be completed.
Under the guidance of the teacher and the tempering of the time, when I come back to this content, I have found some skills for how to ask each question. The third-grade children already have a certain logical thinking ability, but the logic is not very strong. In order to guide students correctly, we should not follow the teacher's ideas, but should try to figure out the students' thoughts and then base their thinking. Traction on the top can often achieve the desired effect more effectively.
At the beginning of this lesson, I still used a fairy tale to introduce the situation, but found that the students' emotions were not as high as my original students. I thought at the time: Is it my fairy tales students have heard before? After class, I asked the students, they said that the story had not been heard before. What is the reason for this different reaction? I thought about it after class. With the popularity of computers, many students now go online from a young age, and they can get a large variety of information from the Internet, which has prompted students to get premature. The children who once liked to watch "Pleasant Goat" reached the third grade, and they began to have contradictions. On the one hand, they usually looked at "Pleasant Goat" and on the other hand began to reject "Pleasant Goat". They think this cartoon is very naive, it is not their age. The children of the paragraph should watch the cartoon. Similarly, the so-called fairy tales are very naive to them, and the interest will not be very high after hearing. In the future class, no matter what is used for introduction, you should first understand the preferences and psychology of the students at that time, and should not stay in the understanding of the original students. The times are changing, the children are changing, and only when they follow the laws of their physical and mental development can they come up with a good lesson.
Later, at the time of the new grant, students can use the concept of the perimeter and the characteristics of the rectangle to derive three formulas for the perimeter of the rectangle. In the application, I found that the students can calculate the circumference of the rectangle correctly. The formula of the circumference of the rectangle is more than the formula of the rectangle. The formula is rarely used by the students. This is the most The simple one, the students do not choose. Is it now complicated? In fact, this method is still the simplest one, except that the students at this stage have not yet learned the number of digits multiplied by one digit. If the question gives a large number, they cannot calculate the result with this formula. This makes me think that the textbook of this volume is actually arranged "multi-digit multi-digit number", but after the "perimeter", if you are teaching, first put "multiple digits by one digit" When you finish the "earth circumference" in advance, they can solve it completely in three ways. At this time, the simpleness of the formula of the circumference of the rectangle = × 2 is reflected. So, do we usually go in the order of the textbooks when teaching? This is worth exploring.

Part 4: Reflection on the Teaching of Rectangular Perimeter

I have taught mathematics for more than ten years. I feel that I have mastered the teaching materials and students very well, but this year I learned that my feelings were wrong when I was teaching the "Cylinder of Rectangles".
After discussing with the students "what is the perimeter of the object", I showed a rectangle to guide the students how to calculate the perimeter of the rectangle. The students began to explore in groups, and the students were highly motivated and committed. Soon, a small hand was lifted up and down. I asked the panelists to report on the results of the collaborative inquiry:
"9+7+9+7=32!"
"9+7+9+7=32!" ......
My preset effect did not appear. I have to further encourage to say: "Who has a better way?"
“9+9+7+7!” A student who usually performs well stands up and speaks.
I was a little disappointed in my heart, but I also encouraged to say: "Good! Who has a better way!"
No classmates raised their hands again.
I said: "Reporting students talk about how you calculated?"
“I measured the length and width of the rectangle, then the two lengths plus two widths. I got its perimeter.” Almost every classmate said.
Seeing that the students can't figure out the formula for calculating the circumference of the rectangle, I am anxious and have to guide the formula hard: I said: "The two rectangles are long, then 9+9 can be represented by multiplication formula 9×2. Wide multiplication The equation is expressed as 7 × 2. Therefore, the perimeter of the rectangle can be expressed by such a formula: the circumference of the rectangle = length × 2 + width × 2. It is also possible to first calculate the sum of one length and one width, and then × 2. The perimeter = × 2."
Next is the classroom exercise, I showed three rectangles for students to calculate the perimeter. Only about half of the students in the class use my formula to calculate, and half of the students use addition.
After this class, I fell into meditation: How did I teach myself in the past? It seems to be the first to tell the students the formula, and then guide the students to use the formula to calculate the perimeter of the rectangle. Nowadays, students are encouraged to explore their own knowledge. If they are forced to die, they are deviating from the requirements of the new curriculum reform. Maybe let the students learn the formula first and then calculate the circumference. It may be higher in terms of academic performance. However, in the long run, students learn the knowledge of death, and their thinking is always imprisoned under the teacher's explanation. For these third-grade primary school students, is it not a more intuitive and understandable formula for the rectangular circumference of the students to be drawn = length + length + width + width? !
Since students don't have formulas in their hearts, teachers can't impose some rigid and abstract mathematical knowledge on them. As long as their algorithms are reasonable, teachers should encourage them. The new curriculum reform advocates different ways to solve problems. There is no such thing in textbooks. Did you specify the rectangular perimeter calculation formula as before? Today they have summed up the best calculations and the best calculation methods. Maybe they will pick the pearl of the mathematics crown in the near future!

Part 5: Reflection on the Teaching of Rectangular Perimeter

First, go deep into the students, choose materials, and create situations.
For a subject, the interests and hobbies of the students are the most important. As the saying goes: Everything is learned. After school, I pay special attention to what students like to play, how to play, and to get inspiration from them. The materials used by students are skillfully and reasonably applied to mathematics teaching, so that students have a close and intimate feeling about the content of learning. For example, when I was studying the rectangular perimeter, when I presented the rectangular cartoon to the students, their "love" was immediately "hot": "A beautiful picture!" Then, I moved the picture to the right. , showing a rectangular picture frame of the shadow picture. The physical picture is in sharp contrast with the frame picture, which not only lays the foundation for understanding the perimeter of the rectangle today, but also lays a foundation for the future study area. At the same time, students really feel that mathematics is rich and colorful, and it is definitely not just a simple calculation, formula, and law. Colorful pictures inspire students' curiosity, making them eager to play, fight, and count
Second, study and play, explore the ability to create and develop.
When students let themselves explore and study the perimeter of the rectangle, the students will list the formulas and use the graph to show the solution ideas, verify the rationality of the calculation method, experience the experience, construct the mathematical model, and experience the most basic scientific research methods. . The teacher sent a picture to each classmate, satisfying their desire to "give me a picture"; "Can you use these pictures to form a new rectangle?" aroused the curiosity that students had. Curiosity and creativity, so they can boldly conceive, create, the same spelling, different solutions in the jigsaw puzzle; or different spellings, the same solution. In particular, when a student divides a square piece of the same size into a rectangle, the two pieces of the picture, the three pictures, and the four pieces of the picture are combined, and the ten pieces and the 100 pieces are combined into a rectangle. By the combination of 2 pictures, 3 pictures, and 4 pictures, the calculation method of the circumference of the rectangle after 10 pieces and 100 pieces of pieces is combined, and several squares are derived according to this rule. The picture is evenly divided into rectangular perimeter calculation formulas. It is a game that improves the learning state of students. It is a game that enables students to learn on the basis of subject, positive, confident, active exploration, and collective cooperation. They participate in the process of knowledge formation, and their thinking is generated here. A qualitative leap, the ability to innovate gradually improved, let me surprise, let me sigh!