Unit 1 Four Operations

The knowledge of the first unit is relatively simple, and the main knowledge includes: the calculation order of the same-level operation, learning the order of the two-level operation and the operation order with brackets, and learning the operation about 0. Before this, students have mastered the problem of two steps from left to right and know the function of brackets, so this unit is like a finishing and extension unit.

(It should be noted that the content of this unit is based on application problems. In the process of solving application problems, it is a small test for students who don't do well in application problems here, because this unit has three-step application problems and more complicated application problems. If you find reading difficult, you must read it several times. Don't worry, you won't do it. As long as you study hard, you will do more and more.

Example 1 is a mixed operation of addition and subtraction, and example 2 is a mixed operation of multiplication and division. They are all operations at the same level, that is, only addition and subtraction or only multiplication and division. Students need to understand that in the formula without brackets, if there is only addition, subtraction, multiplication and division, it must be calculated from left to right.

Example 3 is the addition and subtraction of product sum quotient. There are two levels of operation. For example: 24× 2+24 ÷ 2, students need to remember that there are multiplication, division and addition and subtraction in the formula without brackets, so multiply and divide first, then add and subtract.

The content of Example 4 is similar to that of Example 3, but one thing needs special attention, that is, on the page 1 1, he has a second method of solving problems. In this problem-solving method, brackets appear, so students should be clear about this problem: if brackets appear in the formula, first count the brackets.

Example 5 is a three-step calculation problem with brackets, that is, the result is obtained in three steps. Here is actually an exercise and application of the above study. Students studying here need to sum up their previous knowledge before they can solve the following problems.

Example 6, the calculation of 0 is explained in detail on page 13 of the textbook: 0 cannot be divided. If 5÷0 cannot get the quotient, it should be because a number cannot be multiplied by 0 to get 5. 0÷0 cannot get a definite quotient, because any number multiplied by 0 will get 0.

That's all for this unit, but what I want to say is that students' carelessness is a big problem when calculating. Therefore, the examples of exercise 1 and exercise 2 in the textbook must be practiced in a down-to-earth manner. I did it myself and found that the application problems in it have a lot to do with the application problems in the first volume of grade five. When I was studying equations in the fifth grade, there were many similar types of problems, so I had to practice with my heart. Each one not only requires correct results, but also needs to think about some problems by itself, from which we can understand the true meaning of the four operations. Be sure to ask questions you don't understand, and the teacher will give you detailed answers.