Reflections on the teaching of circumference 1 How to write "circumference" is the content of the third lesson of Unit 10, Volume 10 of Elementary School Mathematics published by Jiangsu Education Publishing House. "The circumference of a circle" is based on the knowledge of the circumference of a rectangle and a square. It is the deepening of the previous research on "the understanding of the circle" and the basis of the later research on "the area of the circle". Therefore, it plays an important role in connecting the past with the future and is an important content in elementary geometry teaching.
Mathematics curriculum standard clearly points out: "The development of modern information technology has a great influence on the value, goal, content and the way of learning and teaching of mathematics education. The design and implementation of mathematics curriculum should attach importance to the application of modern information technology, especially to fully consider the influence of calculators and computers on mathematics learning content and methods, vigorously develop and provide students with richer learning resources, take modern information technology as a powerful tool for students to learn mathematics and solve problems, and devote themselves to changing students' learning methods, so that students are willing and have more energy to invest in realistic and exploratory mathematics activities. "
The topic of this lesson is "circumference". Students don't just learn circles by imitation and memory. Through the use of multimedia teaching means, students' exploration process of pi calculation method is deepened.
The focus of this lesson is to understand the meaning of the circle and the derivation process of the calculation formula. The difficulty lies in understanding and mastering the circumference formula and pi of a circle. Firstly, the bicycle problems in life are shown through multimedia, so that students can guess what the circumference may be related to. How many times the diameter? It aroused the students' desire to explore actively, and then showed the methods of measuring circumference such as "winding" and "rolling" with multimedia custom animation. Through observation and thinking, students can easily master these methods and lay a good foundation for later hands-on operation. Then, students use the prepared learning tools to further prove whether their guesses are reasonable and scientific in the form of group cooperation. And help students who have difficulties to exchange research results and find the law: the circumference of a circle is always more than three times the diameter, thus obtaining pi. With this discovery, students have established a new cognitive structure, so that students can experience new values. At the same time, multimedia is used to show the achievements of ancient mathematicians in China in the study of pi, so as to cultivate students' patriotic sentiments. In the classroom, vivid and interesting exploration contents, colorful multimedia courseware, open and relaxed classroom environment, appropriate encouragement, ideological confrontation of expressing opinions, strict and standardized knowledge expression and personal experience of classroom life will cultivate students' ability of observation, reasoning, analysis, synthesis, abstraction and generalization and their ability to solve simple practical problems, and at the same time cultivate students' hands-on operation ability, innovation spirit and unity and cooperation spirit.
Through the teaching practice of this class, I realized more: as long as we can let go in class, students will have amazing performance. I believe the students can do it!
The mountain road twists and turns, but after all, it extends towards the peak. It is necessary and inevitable to return the classroom to the students. I will continue to explore, try and reflect in my own teaching practice, strive to return the classroom to students faster and better, create an efficient classroom, and return to the essence of education from the all-round development and lifelong development of students.
Teaching Reflection on How to Write a Circle This course is to further learn the calculation of a circle on the basis of students' mastering the general concept of a circle and the calculation of the circumference of a rectangle or a square.
Success:
1, fully understand the concept of perimeter and strengthen the understanding of meaning. Students have learned the concept of perimeter before, and have a certain understanding of the perimeter of rectangle, square, parallelogram, triangle and trapezoid. They know that the length of a closed figure is the circumference of the figure. On this basis, they understand that "the length of the curve forming a circle is the' perimeter' of the circle". In teaching, by reviewing the perimeter of the previously learned figure, and then leading out the theme map, the students' existing experience is enriched through the actual scene, and gradually internalized into the students' understanding of the meaning of perimeter, and it is clear that the perimeter is a line, but this line is a figure composed of curves.
2, strengthen the hands-on operation, explore and discover the law. In teaching, let students use different methods, such as winding rope, winding rope, folding rope, etc., to obtain circles with diameters of 2 cm, 3 cm, 4 cm and 5 cm, and the ratio of circumference to diameter is always more than 3 times, so that students can make it clear that the circumference of a circle is always ∏ times the diameter, and thus the formula for calculating the circumference of a circle is derived.
Disadvantages:
Because the students previewed this part before class, a group of manual operations failed, and the results were all 3. 14 times. It seems that the students do not pay enough attention to the operation, only pay attention to the conclusion of the result, and ignore the presentation of the law.
Re-instructional design:
After teaching the circle, students should pay attention to the difference between a half circle and a half circle, and pay attention to the relationship between the circle and its diameter and radius, that is, when the diameter or radius of a circle is expanded by two or three times, the circle is also expanded by several times, thus connecting the sum of sides, and the surface area and volume of a cube are expanded by several times when the sides are expanded by two or three times.
Reflections on how to write "3 1" in the teaching of "circle", focusing on sustainable development, rearranging teaching materials and guiding exploration.
According to traditional mathematics textbooks, the concept of perimeter is described as the sum of all sides around a figure, which is called its perimeter. However, starting from the overall goal of space and graphics in the new mathematics curriculum and the sustained and harmonious development of students, I strengthened the connection between perimeter and daily life, and let students describe their understanding of perimeter in their own language and fully affirm them one by one. This teaching fully embodies my correct understanding of the new curriculum concept. In teaching, I respect students, carry forward teaching democracy, take students as the subject of inquiry, let students fully expose their own thinking process as far as possible, guide students to evaluate independently and realize themselves, and teachers become organizers, guides, collaborators and participants of students' learning. In the comparison of strategies, it promotes the development of students' cognitive ability and figure perimeter reasoning ability, embodies the teaching idea of teaching mathematics outside mathematics, fully allows students to experience the process of mathematization and re-creation, and provides sufficient time and space for the development of students' personality.
2. Based on solving practical problems, the diversity of algorithms is emphasized.
Calculating the perimeter of rectangles and squares is a special case of calculating the perimeter of graphics. It is obtained through people's continuous summary. Its characteristic is simple and fast calculation. However, for primary school students who are in contact for the first time, whether to pay attention to the results of perimeter formula or to guide students to explore the process of measuring specific figures of perimeter is the embodiment of two different educational views. In the teaching process, I did not adopt the traditional formula-example-exercise teaching structure model, but adopted the new teaching model of problem scenario-guess-model-verification and explanation-application and expansion advocated by the new curriculum.
3. Take a variety of effective strategies to control the inquiry process, so as to be free but not scattered.
The new curriculum emphasizes the diversity of algorithms, so students should be guided. However, when students are allowed to discuss freely, there may be noisy classroom atmosphere, or even out of control. Therefore, in the face of new curriculum teaching, how to make students fully discuss and ensure the smooth progress of the learning process? For these situations, I think we can first have a normal mind and some tolerance, that is, in the process of discussion and communication, some noise is inevitable, but we must grasp two principles: first, noisy things must be related to the topic under discussion, and second, noisy things will not affect others and the teaching process. If these two principles are violated, teachers can no longer sit idly by.
However, this course seems to overlap with exploring new knowledge. It is not necessarily good for students to understand the circumference only by these examples in life. This class can be not limited to books or pictures and objects given by teachers, but can completely contact with students' real life, touch, draw, measure and calculate familiar objects or graphics around them, and perceive the perimeter of various objects through a large number of examples. Also, when deducing the perimeter formulas of rectangles and squares, we are eager to summarize the formulas and ignore the process. In the future teaching, we should emphasize the infiltration of mathematical thinking methods, but we can't pursue any compulsory unity. In the similar teaching of calculating perimeter, students will have different algorithms. Teachers should not rush to generalize their different algorithms into formulas, but let them talk about the reasons for the calculation. In the process of many measurements and calculations, students will gradually master the method of calculating with perimeter formula. Instead, students can experience the algorithms they like or can understand through the process of independent thinking, exploration and calculation, which truly embodies the diversification of algorithms and the new curriculum concept of letting different people learn different mathematics. Of course, for some students who are not good at using the perimeter formula, there is no need to force unity. With the accumulation of experience in calculating perimeter, they can gradually understand the meaning of perimeter formula.