There are no brackets in the first volume of mathematics in the third grade of primary school. Introduction is as follows:

1, master the order of multiplication and division, and calculate correctly.

2. Learn the writing format of mixed operation and calculation process, and develop good study habits.

3. In the process of cooperation and communication, students have enhanced their interest and confidence in learning mathematics.

4. Teaching Emphasis and Difficulties: Emphasis: Explore and master the operation sequence of mixed operations including multiplication, addition and subtraction.

5. Difficulties: The calculation steps are expressed by recursive equations. Teaching method and learning method: teaching method: teaching method and guiding method. Learning methods: independent inquiry method and communication method.

6. Teaching preparation: multimedia courseware and answer sheet. Teaching process: review and introduction. Courseware display. In the formula 12+245, the parentheses are counted first, and then the parentheses are counted.

7. Off-mold calculation. The design intention is to consolidate the old knowledge and let students learn new knowledge naturally by reviewing the knowledge of the last class.

8. Explore new knowledge. Courseware shows examples. Ask the students to find out the information and problems in the questions. Guide students to find out the quantitative relationship. Teacher: How much is a football more than a basketball? Every football has more money than every basketball.

The concept and operation order of four operations

1, addition, subtraction, multiplication and division are called four operations. In the formula without brackets, if there is only addition, subtraction, multiplication and division, it should be calculated from left to right in turn.

2. In the formula without brackets, if there are multiplication, division and addition and subtraction, first calculate the multiplication and division, and then calculate the addition and subtraction.

3. There are brackets in the formula. Count the inside of brackets first, and then the outside of brackets; The calculation order of large, medium and small brackets is small → medium → large. The calculation order in brackets follows the above calculation order of 1, 2 and 3.