Teaching content:

People's Education Edition "Compulsory Education Curriculum Standard Experimental Textbook Mathematics" Volume IV, 5 pages, Example 2.

Design concept:

1. Teachers transform book mathematics into life mathematics by creating rich teaching resources. Close the distance between mathematics and life, and let students feel the fun of learning and using mathematics.

2. On the key points of knowledge (such as the application of bracket teaching), arrange group communication, promote the development of students' cognitive ability and problem-solving ability through the collision of students' thinking, and enhance their sense of cooperation.

Teaching objectives:

1, so that students can find problems from specific life situations, master the steps and methods to solve problems, and know that they can solve problems in different ways.

2, learn to use the bracket column synthesis formula, and understand the role of brackets.

3. Cultivate students' good study habits such as careful observation, and initially cultivate students' ability to find, ask and solve problems.

Teaching focus:

Will use the comprehensive formula in brackets to solve the problem.

Teaching preparation:

Teaching courseware

Teaching process:

First, create a situation

1, Dialogue: The students all went to buy bread with their parents. Today, the teacher worked with everyone to solve the problem of buying bread.

Second, explore new knowledge.

1, using the scene of buying bread. Let the students say the information given in the picture freely. Do you think it's weird (showing the courseware for buying bread)

Teacher: What happened here?

Teacher: Yes, you see how orderly they buy bread. They queue up to buy it. Do we usually line up in the supermarket?

Teacher: Now, there is so much information on the map. (The courseware shows the dialogue: "I made 54 loaves in one breath." "We bought 22 loaves of bread." "We bought eight loaves of bread." )

Teacher: Based on this information, what problems can you solve? ? Students speak freely. The teacher's conscious and purposeful suggestion: How much bread is left now?

2. Group discussion.

1) How do you solve some bread left now?

2) After thinking independently, exchange your ideas in the group.

3) Send group representatives to exchange problem-solving methods in class.

3. Record the students' problem-solving methods on the blackboard.

4. Observe and compare the relationship between the two methods.

Obviously, the result of both methods is to find out how many loaves are left now. What's the difference between solving problems?

5. Question: What should I do if I combine the two formulas solved step by step into one formula?

Students try to make a comprehensive formula by themselves.

1)54-8-22

2) Can it be listed as 54-8+22? group discussion

Communication: What do you think?

6. The teacher introduced a new friend "Scaffold" to everyone today. In mathematics, we usually use a bracket to write this formula as a two-step problem. 54-(22+8)=24 (pieces). Brackets are like two doors, 22 and 8 are close together. When calculating, first calculate 22+8=30 in brackets, and then 54-30=24.

Third, consolidate the application

1, consolidate the application of brackets. ? Teacher: We have made new friends. Parentheses, can you count them?

(Courseware, show formulas in groups. ) teacher: do you have any ideas through calculation? In an equation, if there are parentheses, the parentheses should be counted first. Parentheses sometimes change the order of operations. 2. Question 2 of exercise 1

Ask the students to explain the meaning of the picture and calculate the questions clearly, then ask the students to answer independently. Then find some classmates to talk about how to solve the problem.

Finish the third question independently and tell me what you think.

4. Let students try to solve problem 5.