I think Miss Li's teaching has the following highlights, which are worth learning:
1. Introduce situations, arouse students' enthusiasm and reveal topics.
Introduce the situation of boiled eggs in daily life. How many minutes does it take to cook one egg for 5 minutes and six eggs? Some students say 5*6=30 (minutes), and some students say 5 minutes, which naturally leads to the focus of today's teaching and the choice of the best plan.
Second, pay attention to students' practical ability. When teaching the problem of pancakes, Mr. Li asked students to take out circular pieces of paper prepared in advance to simulate the process of pancakes, so that students could experience the practicality and life of mathematics in hands-on operation and help them choose the best scheme better.
Third, give full play to the team's unity and cooperation ability, so that students can truly become the masters of the classroom. While exploring the best scheme of three pancakes, the teacher handed over the lesson to the students. Ask the students to pose, then fill in the form, and finally report the results to the team leader. In a series of activities, the teacher lets the students go, and the teacher only gives necessary guidance, which fully embodies the student-oriented thought.
Four: Teachers are good at guiding and instructing students. Finally, the teacher organized the students to observe the form carefully and encouraged them to "What did you find?" . Let students speak freely and think differently. In class, some students found the law that "the number of cakes increases 1 and the number of minutes increases by 3" at a glance, but no students came up with the method mentioned in the teaching reference book. The teacher instructs the teaching in time. If the number of cakes to be branded is even, you can brand two. If the number of cakes to be branded is odd, two cakes can be branded first, and the last three cakes can be branded according to the above optimal method, which saves the most time. "
Suggestion:
1. When the group reports the problem of flipping three cakes, the teacher might as well stick a little blackboard writing on the blackboard to facilitate students' understanding in the next step, because the front and back sides of the three cakes should be clearly explained.
2. When the group leader reports, the teacher should give the students ample opportunities to express their ideas, so that after the students finish speaking, the teacher can explain and guide them, and don't rush to interrupt the students' thinking.
When working in a group of four, I found that basically only two people in each group participated, and the other two did not. Teachers might as well do activities in pairs, so that every student has the opportunity to operate. Mingming turned over three cakes, and the teacher asked the deskmate to talk about the best plan just now. I think there are some restrictions on students' thinking, so students should be allowed to think according to their own ideas.
4. In teaching, I think teachers should guide and guide the best plan in a certain order: "How many cakes should be baked-how many sides should be baked for a * * *-at most two sides at a time, at least several times-and finally figure out how many minutes it takes", which is easier for students to accept step by step and is also conducive to students' final understanding of the law.
When the final rule is presented, I think the rule of "number of cakes *3= number of minutes" is actually simpler, more intuitive and more in line with their understanding characteristics. If the number of cakes is divided into odd and even numbers, students will be confused.
Pancake problem is the content of the first volume of compulsory education curriculum standard experimental teaching material, which is published by People's Education Publishing House. This paper mainly discusses how to arrange homework reasonably to save the most time and let students experience the application of optimization thought in solving problems. Pancake is a common housework in our daily life, but it contains profound mathematical problems and thoughts. The purpose of textbook arrangement is to let students try to find the best solution from a variety of solutions through simple pancake examples in daily life, so as to infiltrate students with the idea of optimization, let students experience the role of overall planning in daily life, and let students feel the charm of mathematics.
First, cut to the chase, introduce new lessons, and reflect the beauty of simplicity.
In this lesson, the teacher started teaching with the clue of "everyone in the class bakes a cake", grasped the students' curious nature, designed the life scene of "baking a cake", directly exposed the topic and introduced a new lesson. In this way, students can not only understand what they have learned in this class, but also quickly concentrate their attention and stimulate their interest in learning mathematics. Simple and clear, reflecting the beauty of simplicity in mathematics.
Second, pay attention to questioning, highlight details and reflect the beauty of details.
Teacher Fang pays special attention to the detailed questions in this class. He can listen to students carefully, ask questions when students are ambiguous, ask questions when students don't understand, ask questions when key and difficult points break through, ask questions when the classroom is generated, and pay attention to generation and guidance. From the questions, we can see Mr. Yu's guiding art and his pursuit of the beauty of details in mathematics.
Thirdly, it breaks through the teaching difficulties of textbooks and permeates the idea of optimization.
At the beginning of the class, Mr. Fang made good use of the method of one cake and two cakes and asked the students: Why is the baking time of one cake and two cakes the same? So that the students initially established the concept of saving time by baking two cakes in one pot at the same time. Then discuss with the students how to bake three cakes. In this process, students are organized to discuss, report and demonstrate at the same table, and then students discuss to form a plan for baking cakes, show the students' plans, compare and distinguish the differences between the two plans, so as to optimize the plan. The method of flipping three cakes is the key and difficult point here. Let the students discuss, cooperate and explore this problem, then solve the problem, and then use the table to find time to make four, five, ... these cakes. The purpose of this treatment is to reduce the difficulty of the topic, help students think and solve problems, and then guide students to observe the table and discuss which is more convenient, the ordinary flipping method or the quick flipping method. "What did you find?" Ask the students to choose the best plan through observation and comparison, and finally sum up as: number of cakes × time required for a cake = time required for number of cakes. The whole process of baking cakes is step by step, cultivating students' mathematical thinking.
Revision 3 of "Mathematical Wide-angle Pancake Problem" in Grade Four Pancake is a math course that permeates the whole optimization idea, and it permeates the simple optimization idea through simple optimization problems. In the teaching design and teaching process, pancakes are the theme, and the learning of mathematical thinking methods is the main line. How to eat pancakes as soon as possible? Start teaching. The query flow of baked 1, 2, 3- single and double cakes is designed. Taking flipping three cakes as the teaching breakthrough point, the consciousness of finding the best scheme from various schemes is formed, which provides students with time and space for independent thinking, hands-on operation, cooperative exploration and exhibition. Students use small disks instead of cakes to experience the process of putting forward and solving mathematical problems, discovering mathematical laws and building mathematical models. The whole class is permeated with the following ideas:
1, let students practice freely.
Curriculum Standard points out that students' mathematics learning content should be realistic, meaningful and challenging. In class, the teacher asked the students to make pancakes with a round piece of paper instead of cake. This link allows students to participate in the process of knowledge generation, perceive in operation and sublimate in practice. Students are also required to use learning tools to simulate pancakes at the same table. One person makes pancakes, and one person records them.
2. Let students speak freely.
In class, the teacher asked the students to communicate, show and communicate with the whole class in groups. This link realizes the equal dialogue between students and between teachers and students, which is not only the interaction between students, but also the interaction between teachers and students. Through mutual communication, learn from each other's strengths, constantly improve their cognitive system, and form an organized and regular knowledge structure. When studying how long it takes to bake three cakes (this is the focus and difficulty of this course), everyone has never used the method of baking one cake after another, but there are many ways to bake one cake after two cakes appear, and individual groups think of baking alternately. The teacher asked the students to demonstrate by hand, and everyone basically understood. Later, everyone knew that we should make full use of the condition that we can bake two cakes at a time.
I think if this class can give children another development lesson, it can be arranged at the end of the class. What if there are 4 cakes, 5 cakes and n cakes to bake? What did you find? Directly find out the rule that the number of cakes is 3 = time. The result is: if the number of cakes to be baked is even, you can bake two pieces; If the number of cakes to be baked is odd, you can bake two pieces first and the last three pieces according to the above optimal method, which saves the most time. Students' findings are actually simpler and more intuitive. Mathematics teaching is not only the result of imparting knowledge, but more importantly, exploring the formation process of knowledge. It is not only a place to carry mathematical knowledge, but also a place for students to develop in an all-round way. Only by constantly strengthening learning and improving professional skills can teachers give students an innovative classroom and a developing classroom.