For example, children are in a row of Xiao Ming's, three people in front and four people behind Xiao Ming ask you, how many children are there in this row?

So you need to use 3+4+ 1, and this is Xiao Ming, because there are no three people in front, including Xiao Ming, so when calculating the total number of people, Xiao Ming should be included.

The situation of subtracting one is as follows:

The children in the first row are counted from the front, the third row and the fourth row behind. How many children are there?

In this case, 3+4- 1=6 people are needed. Because Xiaoming is counted from the front and the back, there are two Xiaoming in 3+4, and one Xiaoming is 6 people.

Primary school mathematics is to teach children a series of knowledge about number, four operations, the calculation formula of figure and length, unit conversion and so on through textbooks, which lays a good mathematical foundation for junior high school and daily life calculation.

Frieden Noel, a Dutch educator, said: "Mathematics comes from reality and must be rooted in reality and applied to reality." Indeed, modern mathematics requires us to observe the world from a mathematical perspective and explain the world in mathematical language.

Judging from the mathematics learning psychology of primary school students, the learning process of students is not a passive absorption process, but a reconstruction process based on existing knowledge and experience. Therefore, learning while doing and learning while playing will make children learn more actively.

From our educational goal, while imparting knowledge, we should pay more attention to cultivating students' comprehensive ability of observation, analysis and application.