How to teach children math addition and subtraction within 20?

Fingers quickly calculate secrets.

Elementary: Addition within 100

Preparation: Before reading the following formula and playing related finger games, the teacher needs to give the password "Clear", and the children will clap their hands immediately, then hold their fists on their chests and concentrate on getting ready. (Note: the palms are inward, and the distance between the two fists is based on the convenience of the fingers, not too close or too far. )

First, the finger positioning formula

I have a pair of hands, representing ninety-nine; Set the left hand to ten, and I can count to ninety;

Pose your right hand and count from one to nine; It's convenient to add and subtract, so don't worry about calculation.

Second, the hand index formula

The index finger extends "L" and the middle finger extends "2";

The ring finger is "3" and the little finger is "4";

Four fingers and a thumb, the thumb is "5" to remember;

Then extend the index finger to the little finger, and "6", "7", "8" and "9" are arranged in numbers.

Third, the right hand points out the exercise formula.

Take the lead, two tigers contend, in a few words, the four seas are at home, and the grain is abundant.

Six animals are thriving, and the eight immortals are crossing the sea, and nine Niu Yi hairs are urgent.

A word nine, two dragons playing with pearls, three pillars separated, surrounded by enemies, the grain is abundant.

Six gods without a master, seven ups and downs, exquisite, nine Niu Yi hairs, perfect.

(Note: When reading "urgent" or "perfect", make a fist in your right hand and put "1" in your left hand, indicating carry. )

Fourth, the left hand points out the exercise formula.

Ten, twenty, thirty, forty; Fifty,

Sixty, seventy, eighty, ninety, one hundred.

(Note: When reading "100", clap your hands, and then put your fist on your chest. )

Five, two-handed counting exercises

15、23、46、99、58、73、6 1 ……

(Note: Choose the number according to the cognitive level of children of all ages. )

Six, addition exercises

Note: When doing addition exercises, such as "3+5", the right hand will give out "3" first, and the process of "+5" is: say "plus 1" in your mouth and extend your little finger; Say "plus 2" in your mouth and stretch out your thumb with four fingers (note that the thumb only represents "1" in the process of pointing out, and the thumb is only regarded as "5" when deciding the number); Read "plus 3" in your mouth and stretch out your index finger; Read "plus 4" in your mouth and stretch out your middle finger; Say "plus 5" in your mouth and extend your ring finger. At this time, counting began, only the little finger of the right hand did not open, and the result was "8".

(1) single-digit addition exercise (addition exercise within 10)

1+ 1

2+ 1、2+2

3+ 1、3+2、3+3

4+ 1、4+2、4+3、4+4

1、5+

2、5+

3、5+

4、5+5

1、 1+

2、 1+

3、 1+