Let's look at this example, 12-8, how to make first-grade pupils understand arithmetic?

First of all, you can put 12 in kind, and there are many items that can be used at home, so that children can really see the items of 12. Then, put ten items in a group and the other two in a group.

Let the first-grade pupils understand that 12-8 cannot be reduced directly. You can subtract 8 from the first set of numbers 10. Because when the first grade was published, everyone was very firm in the concept of good friends, that is, 1 and 9 are good friends, 2 and 8 are good friends, 3 and 7 are good friends, and 4 and 6 are good friends. On this basis,

Next, let the children understand that the result of 10-8 needs to be added with the second set of numbers 2, which is the final correct result.

Of course, using the inverse operation of subtraction and addition, we know that 8+4= 12, so 12-8=4. This method is also feasible.

Ten-point method:

Calculate by ten: 9+3.

The answer is as follows:

Divide 3 into 1 and 2, because 9 adds up to 10 and lacks 1, so divide it by 1.

So 9+3, the decomposition calculation is 9+ 1= 10, and finally 10+2= 12.

Oral arithmetic is a very important ability for primary school students. The improvement of children's oral calculation speed can save some learning time, improve learning efficiency, improve children's interest in learning mathematics, and help children build or enhance their confidence in learning mathematics well.

In the mathematics teaching of grade one or two in primary schools, the method of "adding up to ten" is often used to calculate the addition and subtraction within 20. Ten is a crutch. 10 can be decomposed into several and several, and several and several can make up 10. As long as you master the decomposition and composition of 10 quickly and accurately, you will be able to calculate the addition and subtraction within 20 correctly and quickly.