Reflection on the second volume of mathematics teaching in grade four and triangular classification are one of the key contents of this unit. The design intention of the new textbook in this unit is to strengthen the understanding of various graphic characteristics through students' classification of graphics. In order to improve students' learning of mathematics knowledge with the help of modern learning platform, I designed the teaching idea of this course.
I designed six links to help students understand the classification of triangles. The first link is scoring. Let the students work on boats made up of different types of triangles.
The triangle is decomposed and classified. In the default time, I hope students can use their imagination to classify, so I didn't restrict students from classifying according to the size of the angle from the beginning. Students are likely to classify similar shapes according to their own understanding. I imagine that when it is generated, it can be classified according to different classification methods and angles. But the actual situation is that my guidance in this place is not in place, which is a bit of a drag. Finally, I abruptly pulled the students to the idea of classifying by angle, and lost the meaning of guiding generation. The second link is speculation. The purpose of this link is not only to consolidate the classification by angle just now, but also to prepare for the classification by edge below. So I guess most of the triangles prepared in this link are special isosceles triangles or equilateral triangles. I'll hide two corners first, and only reveal one corner for students to guess. When the exposed angles are right angles and obtuse angles, students can quickly guess right triangles and obtuse triangles. When guessing an acute triangle, I first reveal an acute angle, so that students can't guess what triangle it is at once, and then reveal an acute angle. Most students know it is an acute triangle without looking at the third angle, so some students take it for granted that as long as two angles are acute, they can be judged as an acute triangle. Finally, I deliberately took out two acute angles of an obtuse triangle and asked them to guess whether it was an acute triangle. Students realize from the guess that only two acute angles can't be sure to be acute triangles, but all three angles are acute angles. After finishing the understanding of classification by angle, I asked the students to carefully observe the triangle just guessed and asked them to classify it again in other ways than by angle. From the teaching practice, it is still difficult to directly ask students to reclassify many students in this way, and quite a few students are still classified according to the angle just now. Not many people can really think of classifying by edges, and a big problem in computer operation is that students can't measure the length of each edge. Although MP-LAB has measuring tools, it is unrealistic to require every student to operate flexibly. After the students finally separated isosceles triangle and equilateral triangle, I set some judgment questions in time to consolidate my understanding of the above classification. The latter two links need students to do it themselves. One is drawing, which requires students to draw acute triangle, right triangle and obtuse triangle on the computer with MP-LAB tools. This design makes full use of the convenience of computer tools. By drawing a picture, students can have a deeper understanding of triangle classification and improve their understanding of triangle classification to a practical level. In the last cutting session, students are required to use MP-LAB scissors tool 1 to cut out two triangles in a rectangle, one isosceles triangle in a rectangle and four isosceles triangles in a square. These problems deepen step by step, which puts forward higher requirements for students' spatial thinking ability and understanding of triangle characteristics.
But judging from the actual teaching effect, the effect of this course is very poor. Carefully summarize at least the following shortcomings:
1. Lack of sufficient psychological preparation for math class in the computer room. In the process of computer operation, the teacher is not skilled in the use of the machine, which leads to a long time when the classroom is almost out of control because of improper machine operation.
Second, when the teacher's guidance is not in place and the preset situation does not appear, the teacher lacks enough wit to guide the generation, but mechanically copies the lesson plan, which makes the classroom lose its original vitality.
Third, the students in this class have poor expressive ability, most of them dare not express their ideas boldly and accurately, and their conformity psychology is outstanding, so they can't really exert their thinking ability.
The problems exposed in the above teaching make me clearly see my own shortcomings in all aspects, especially in the basic teaching skills. It is a beneficial attempt to take math lessons in the computer room, and it is a gratifying harvest to accumulate first-hand teaching experience in this field.
The second part of the second volume of the fourth grade reflects on mathematics teaching. What should teachers not design teaching links for? Algorithm diversification? And then what? Diversification? . What if students just list various algorithms and scratch their beards and eyebrows? Then students' understanding of each algorithm is only different in form. So when some teachers say? Calculate in your favorite way? Sometimes, students will return to the original point of understanding and insist on solving problems in their own way. Because they have not been popularized in the process of algorithm diversification.
Students should not only understand the diversity of algorithms, but also understand the rationality of algorithms. In this way, students' understanding of algorithms will not only stay in the commonly used algorithms provided by teachers or their favorite algorithms, but also gain the development of thinking in the process of algorithm diversification. In this lesson, for? 0.85+ 1.6+2.4? This formula, a classmate said: I will work out 0.85+ 1.6 first, and then add the total to 2.4. ? I guide students to explain the process of this algorithm: actually? From left to right? . So when some students reported using vertical calculation, many students found that the operation order of this algorithm is also? From left to right? It's just the difference in writing form. It can be seen that after guidance, students can consciously induce and deepen their understanding of the two algorithms. Some students used the law of addition and combination, first calculate 1.6+2.4, and then add 0.85. At this time, I further guide students to establish the connection between decimal operation and integer operation, make students realize that the law of integer operation is also applicable to decimal, communicate the connection between decimal operation and integer operation, and further improve students' thinking.
An algorithm to guide students to pay attention to and understand others
In computing teaching, teachers should guide students in time and pay attention to other people's different algorithms. It can guide students to summarize and improve different algorithms, and for some problems, students need to discover the internal relations between various algorithms. This process should be realized through students' independent communication after all students have fully experienced the process of optimizing the query algorithm. In this lesson, I designed two small questions that are worth exploring in shooting games. Question 1: Who has the highest total score, the younger brother or the younger sister? Immediately, some students answered, adding up the three scores of brothers and sisters respectively to calculate the total score and then compare it. At this time, some students began to write, and some students can already do oral calculations directly. I didn't rush to comment, but waited for their results. At this time, a few students didn't do verbal calculations, but just looked at the data on the big screen. Finally, a classmate raised his hand: Teacher, I can find that my brother's total score is high by observing these two sets of data without calculation. ? Distribute among students? Hehe? Oh, the sound of 1, several students raised their hands at the same time. I asked this classmate to continue: The first time my brother was 0.3 points higher than my sister, and the third time my brother was 0.3 points lower than my sister, which was equivalent to a tie. The second time, my brother scored higher than my sister, so my brother scored higher? . At this time, a burst of applause broke out automatically among the students. I think this applause fully proves that the students themselves have realized the value of this algorithm.
Reflection on Mathematics Teaching in the Fourth Grade The third part "Laws in Graphics" is the first lesson of the follow-up study of Cognitive Equation in the fourth grade unit of primary school of Beijing Normal University. Exploring the law is the new content of the standard experimental teaching material of mathematics curriculum, and it is also one of the new changes in the teaching material reform. It contains profound mathematical thoughts, and cultivating students' thinking is one of the most basic knowledge in their future study and life. In this class, I preset five math activity plans: 1, pre-class activities. 2. Create problem situations and get to the point. 3. Explore laws and experience methods. 4. Apply the rules. 5. Class summary. Effective mathematics activities mean that teachers need to awaken, guide, promote and motivate students to learn? Initiative? , constantly triggering the internal needs of students' learning. Is this an effective mathematical activity? Engine? . First of all, what teachers should do is to find out students' knowledge, and at the same time, give students the motivation to learn and stimulate their inner needs. So, I created a problem situation:? Students, can you put the most triangles together with nine sticks? Students who put a small number of triangles may be able to tell the answer at once by naked eye observation, but they may not be able to tell the answer at once by a large number. This challenging learning task has aroused students' cognitive conflicts, and initially made students experience the necessity of exploring and discovering laws. With what? Guess what? Verification? Teaching methods, let students explore the law independently. 1, encourage students to guess boldly and guess how many sticks are needed to place 20 triangles. 2. Cultivate independent thinking and inquiry methods.