1. Find the whole of the known part (by addition): What is two? When two numbers are added, one is added. Add two numbers and subtract one. When two numbers add up, they don't count as one.

2. Find the part of the known whole (by subtraction): two numbers, minus one by size, plus one by size, plus one by size, plus one by size, plus one by size and plus one by size.

It is necessary to find out the order and direction of queuing, taking the position of people (or things) as the standard. When calculating the total number of people, if people (or things) are calculated twice,1will be subtracted; If there is no calculation, on the contrary, add 1. Cannot be repeated or omitted.

The key to solve this kind of problem is to skillfully use drawing, find out the repeated parts, and then answer. First of all, I will give you a detailed summary of the knowledge points involved in the queuing problem:

Element:

(1) direction: front, back, left, right, head and tail.

(2) Keywords: how much, which one, between A and B, from A to B.

Methods: (1) orientation (2) position (3) marking conditions and questions (4) looking at pictures.

Example:

1. 4 people in front and 3 people in the back. How many people are there in a * *?

2. How many people are there from the back row to the fourth row and from the back row to the third row?

3. The first four people are the third from the bottom. How many people are there?

In the mathematics curriculum of the first grade of primary school, children are usually investigated for a mathematical problem closely combined with life, which is what we often call queuing problem. Learning this kind of problems can cultivate children's ability to combine numbers with shapes and solve practical problems through drawing.