Exquisite learning network has compiled the relevant contents of the first volume of the fourth grade mathematics handout "The Law of Business Change" for you.

1. Teaching content: Mathematics Teaching Standard Edition for Grade Four, Volume 1, Unit 5, Example 5 "Changing Law of Quotient", and Chapter 3 "Constant Law of Quotient".

Second, teaching material analysis

"The changing law of quotient" occupies a very important position in primary school mathematics. It is the basis of simple division operation, and it is also the basis of learning basic properties such as fractional multiplication and division, fraction and ratio in the future. In the textbook, students' existing computing skills are used to ask questions through calculation and comparison, and to guide students to think about the changing law of discovery quotient. This part of the content can not only consolidate the knowledge of calculation, but also cultivate students' preliminary abstract generalization ability, as well as good study habits of being good at observation, diligent in thinking and brave in exploration. This lesson taught by Teacher Pei is based on the changing law of divisor and quotient, and the changing law of divisor and quotient. Because of the foundation of early learning, students have no great difficulty in language expression and thinking, and it is easier to learn.

Third, teaching objectives, key points and difficulties

The teaching objectives of this lesson are:

1. Through observation, comparison and exploration, students can find the law that dividend and divisor are multiplied or divided by the same number (except 0) at the same time, and the quotient remains unchanged.

2. Cultivate students' ability of preliminary abstract generalization.

3. Cultivate students' good habits of observing, thinking and exploring.

Teaching emphasis: through observation, comparison and discussion, we can discover the changing law of quotient.

Difficulties in teaching: Understanding the synchronicity of dividend and divisor, and the same change of dividend and divisor when the quotient is constant.

Fourth, teaching ideas

1. Give full play to students' main role and explore independently.

The teaching content of this lesson is based on the previous study of two laws. Through the study of this lesson, the three laws are perfected, which makes the changing law of quotient more complete and lays a solid foundation for students' future mathematics study. Through the implementation of classroom teaching, students are guided to actively participate in the process of exploring and summarizing laws, so that students can realize teacher-student interaction and student-student communication in the process of observation, thinking, trying and communication, and promote students to actively participate in the formation of knowledge.

2. Grasp the growing point of students' knowledge and effectively extend students' knowledge and ability.

By studying the invariable law of quotient, this lesson grasps the growing point of students' knowledge on the basis of students' initial perception of the changing law of dividend, divisor and quotient, and expands the scope of students' knowledge from simple formula calculation to the relationship between formulas. Let students experience the general process of producing or discovering mathematical laws through the research in this lesson.

3. Try to guess-verify-summarize the conclusion of mathematics learning methods and learn to analyze problems dialectically.

This lesson allows students to make a preliminary guess according to their own thinking in their usual oral arithmetic practice. Whether this guess is correct and universal needs strict verification. In the process of verification, students not only learn to prove their conjecture from a wide range of positive examples, but also learn to comprehensively analyze and cite counterexamples from the opposite side to make the conclusion more comprehensive and correct. It is a breakthrough for students to cite counterexamples. It is of great significance for students to analyze and solve problems with reverse thinking. Throughout the class, students participate in the process of acquiring knowledge and try this method of mathematics learning in the process of guessing, verifying and summarizing conclusions. It shows that the new curriculum standards not only pay attention to students' learning results, but also pay attention to students' learning process, not only their knowledge and skills, but also their emotional attitudes and values.

Teaching process of verbs (abbreviation of verb)

(A) the creation of situations, the introduction of new courses

The teacher showed: 900÷25=? =36 6000÷ 125=? = 48 Ask the students to calculate the results orally. The latter question was very difficult, so the students couldn't work it out, but the teacher worked it out easily, leaving the students in suspense.

(2) independently explore and discover the law.

1, preliminary discovery rule

A set of oral calculations:

14÷2=7 560÷80=7

140÷20=7 5600÷800=7

280÷40=7

Observing this set of formulas,

It is concluded that when the dividend is multiplied by 10 and 2 is divided by 2, the divisor also changes, but the quotient remains the same.

2, gradually improve, let students give examples to verify the law we just found.

Ask the students what else they have found. Do all the figures conform to this law?

Dividend and divisor multiplied by 0 cannot be highlighted at the same time. [Primary school teaching design network -www.xxjxSJ.cn- more math classes]

(C) the application of feedback exercise method

This part is divided into four levels for learning.

1, direct application of law: page 94, question 4: From top to bottom, write the quotients of the following two questions according to the quotients of question 1.

72÷9= 36÷3= 80÷4=

720÷90= 360÷30= 800÷40=

7200÷900= 3600÷300= 8000÷400=

2, the application of the law increases the difficulty, so that students can realize the convenience of calculating the application law: 1400000÷200000=

3. By judging which formula's result is equal to the quotient of 48÷ 12=4, talk about the practice of reasons, and further deepen students' understanding and application of the law.

① (48÷4)÷( 12÷4) ② (48×5)÷( 12×5)

③ (48×3)÷( 12÷3) ④ (48÷3)÷( 12÷4)

4. Examine students' flexible grasp of the law. Through the question of 900÷25, let the students multiply the dividend and divisor by 4 at the same time, and then simplify the complex.