First, add type:

1, knowing one part and the other part, find the total.

Example: Xiaoming keeps 8 gray rabbits and 4 white rabbits at home. How many rabbits does a * * * have?

Think: One part (8 gray rabbits) and the other part (4 white rabbits) are known. Find the total.

Formula: 8+4= 12 (only).

2. Given the decimal and the difference, find the larger number.

Example: Xiaoli's family has 4 domestic white rabbits, and there are 3 more gray rabbits than white rabbits. How many gray rabbits are there?

Thinking: Given the decimal number (4 white rabbits) and the sum of the phase difference (3 gray rabbits are more than white rabbits), find the large number. (Only the number of grey rabbits. )

Formula: 4+3=7 (only).

Second, the types of subtraction:

1, know the total and part of it, and find the other part.

Example: Xiao Li keeps 12 rabbits, including 8 white rabbits and the rest are gray rabbits. How many gray rabbits are there?

Think about it: we know the total number (12 rabbits), and one part (8 rabbits), and find the other part (how many gray rabbits are there? )

Formula: 12-8 = 4 (only).

2. Given the sum and difference of large numbers, find the decimal number.

Example: Xiao Qiang has eight white rabbits, three of which are more than gray rabbits. How many gray rabbits are there?

Thinking: Given the large number (8 white rabbits) and the difference (3 white rabbits are more than gray rabbits), find the decimal number (how many gray rabbits are there? )

Formula: 8-3 = 5 (only).

Primary school mathematics learning methods;

1, pay attention to the cultivation of children's computing ability.

Addition and subtraction within 20 is a very important basic knowledge. Children must learn well and reach the level of skilled calculation. The final speed requirement is about 8 step-by-step calculation questions per minute (referring to the number directly filled in), and the correct rate is 90-95%. Because children have different foundations, the proficiency and speed of calculation vary from child to child.

There are many ways to practice calculation, such as making cards for children to practice independently, or doing housework and taking children out to play.

2. Master the basic knowledge of clever calculation and quick calculation.

Calculation is the first problem that students encounter when they study. To learn math well, they must first pass the calculation. If we can find some rules in the seemingly chaotic formula and simplify it, then students will definitely enhance their confidence and interest in learning mathematics.

First of all, know and learn to count various basic figures: square, cuboid, circle and cube are the most common figures in primary school learning. Through systematic guidance, the first-year students can calculate the number of various basic figures, so that students can establish orderly thinking and lay the foundation for establishing thinking patterns.