Comparison of scores in the first volume of the fifth grade of Beijing Normal University Edition. Textbooks are arranged after learning the meaning and nature of scores and least common multiple, and the concept of "total score" is introduced in the process of comparison. The textbook creates a situation of "campus" comparison, which leads to the comparison of two scores. The textbook provides three ideas: the first is the combination of numbers and shapes, which compares the sizes by drawing according to the meaning of scores; The second is to divide two fractions into fractions with the same mother number according to the law that the fraction size is unchanged, and then compare the sizes according to the method of comparing the fractions with the same denominator. On this basis, the concept of comprehensive score is introduced. The third idea is to change two fractions into fractions of the same molecule, and then compare the sizes. In teaching, students should be encouraged to explore independently and reflect the diversity of comparative methods.

Understanding of students

The methods of comparing scores of different denominators mainly include: dividing the scores first, then comparing the scores of the same denominator, or changing the numerator into the same denominator. Fraction size comparison method with the same denominator and numerator as 1 In the process of preliminary understanding of scores, students have a preliminary understanding. As far as students are concerned, two important components of the comparative size method have been learned. This lesson is mainly to guide students to think about "changing differences into similarities", and to convert scores with different denominators into scores with the same denominator or numerator, so as to communicate old and new knowledge, understand the score at the same time and learn the method of score.

Teaching objectives

Based on the above understanding, my teaching objectives for this course are as follows:

1. Exploring the method of comparing scores will correctly compare scores of different denominators.

2. Understand the meaning of generalization points and explore the methods of generalization points, and you will get the correct generalization points.

3. Improve students' ability to explore knowledge through the research of various methods.

Teaching emphasis: master the comparison methods of different denominator scores, and master the concept of total score in comparison.

Difficulties in teaching: key points of understanding

Firstly, the initial perception comparison method with different denominator scores is introduced.

1, today we will study the size of the score (show the topic)

2.( 1) Look at two scores first: And who is bigger? How do you judge?

(2) What about these two scores? and

Let's take a look at this picture again (showing the theme picture).

(1) Look carefully, who do you think occupies a large area? Reason.

(2) Who is right? Let's take a look together. What are we comparing?

Can you quickly judge their size by the way we just did? Why?

(3) It seems that we have encountered a new situation: the denominator is different and the numerator is different.

(4) What method can be used to determine who is older? Try to write down your thoughts.

Second, explore the method of judgment, so as to get the total score.

1, try to compare,

After students think independently,

Teacher: Share your thoughts in the group and report.

The design of this link gives full play to students' subjectivity and respects students. Starting from the existing knowledge level of students, try to experience it first and try to solve the problem in different ways. )

2. Learn by yourself and understand the concept of general points.

(1) The students are very clever and come up with different ways to compare the size of the playground, which means that the playground is big. Please turn to page 53 and see what else is introduced to us in the book.

(Introduce the concept of universal integral)

How does this book introduce the general points? Let's read together.

Please look at the blackboard carefully. Which of the above four methods is compared with the total score method?

Students found an important point about the total score: scores with different denominators should be converted into scores with the same mother number, so that the units of scores can be unified and the sizes can be compared by the methods they have learned before. Here, the same fraction is called the common denominator.

(3) Please see Mr. Zou's general comment:

=

=

Do you have anything to say?

What else should we pay attention to about common points?

(4) Can you say what a general grade is in your own language?

Now that you have a certain understanding of the score, let's try it. Show:

Divide peace and harmony.

Try it independently first, and the teacher will collect various practices and show them. Guide students to discuss collectively.

(1) Check first. Are these practices correct?

2 that's right. What did you find?

(3) Which one do you like?

4. Summary: Today, we use many methods to compare the scores of different denominators, and we also understand that one of them is called the total score.

The third link

Consolidate new knowledge (practice)

Teaching reflection:

Thinking 1: Is it "innovative use" or "scripted"?

With the above guiding ideology, I have carefully studied the textbook, and feel that the space of the sum of the two scores given in the textbook is too small, which is not conducive to students to compare the sizes in various ways, so I want to use the theme map in the book instead of the size of the sum, so that "1" can be compared in this way. When discussing with our math teacher, a teacher asked me why I changed the theme map and suggested that I think more about why this theme map is here. With this question, I began to read the textbook carefully again, only then did I realize that this theme map can guide students to intuitively perceive and sum up, and the purpose of choosing the textbook and these two numbers is to avoid too many comparison methods, but it is easy to dilute the focus of this lesson. So I decided to respect the textbook "doing things by the book". In this way, the three sections of this lesson have been preliminarily decided. First, the size of sum is preliminarily perceived; second, the total score is understood on the basis of exploring and comparing the size in various ways; third, the comparison problem is solved by using the total score.

Thinking 2: How many key points can a class have?

In order to guide students to compare their grades in various ways, we designed a four-person group activity in the second part to facilitate students to broaden their thinking in the group and learn to learn in group communication. At the same time, I hope to use the group report as a platform to trigger discussion and thinking in the whole class. But after the lecture, our math teacher asked me two more questions. What is the focus of this lesson? A class has been guiding students to discuss the method of comparing sizes for nearly 30 minutes. What do students think is the focus of today's study? I am speechless. Yes, although there is a problem of improper time control in organizing students' reports in this course, although I am well aware that the focus of this course is general grades, I can't give up the method of guiding students to discuss the size of grades, but this will make students confused about the focus of this course. And there may be two points in a class? This question triggered a discussion among the teachers of the math group in our school. In our discussion, I clearly realized that the various methods in this class are just scenarios, which are set up to make students understand the concept of total score more easily. Students can naturally compare scores in this way when they study the total score. So the problem I want to solve at present is how to effectively control the time when guiding students to explore the method of comparing scores independently. My strategy is to use evaluation skillfully, that is, when students need to discuss and think deeply, I ask them to evaluate, and when the discussion deviates from the theme, the teacher will evaluate again.

Thinking 3: Is the concept of "general score" taught by the teacher or read by the students themselves?

The textbook of Beijing Normal University has always discouraged students from learning by rote, so there are few conclusions or concepts in the math book, and the concept of total score in this lesson in the book is very precious to me, so I arranged for students to study by themselves here from the beginning when designing the lesson plan, hoping that students could read something. But in the trial, I found this simple sentence, which seems very simple to me, confusing for students to read and difficult to understand. I can't help wondering, since this concept is so difficult, should I speak directly? But I really don't want students to miss a chance to face books, so I took my question to the math group in our school for discussion. Everyone agrees that the concept of total grade must be read by students themselves, but our teacher must lead them. Here, instead of guiding them how to read, it triggered their discussion, so that they need to read the reasons from the concepts here. Therefore, in this reading session, we designed two activities to arouse students' discussion: First, we found out which one was compared with the total score method from various methods. Second, look at the teacher's mistakes. Sure enough, the students' thinking was detonated by me, and a heated discussion was held around the total score.

From this in-depth study of the new textbook, I feel it is very difficult to really understand the new textbook. We need to keep in touch and think carefully. The most important thing is to consider the actual situation of students and ask yourself "Why?"