How to teach children to learn addition and subtraction within 20

The addition within 20 mainly adopts the method of adding to 10, so that children can practice more after understanding arithmetic. Of course, we can't just let him do the problem. We can let him learn mathematics and do it in life, which will stimulate the child's interest and give him a sense of accomplishment. After learning addition well, subtraction is simple, because the abdication subtraction within 20 is completed by addition and subtraction.

No carry addition and subtraction within 20

The numbers 1, 1 1-20 can be played with children. Describe numbers in three ways:

1) bit is 2, and the tenth bit is 1.

2) 1 ten, five one.

3) greater than 1 1 and less than 13. Describe the numbers in these ways and let the children guess, or conversely, the children describe the guesses of adults until they are proficient.

2. Dial the number with the counter. Parents say the number and children dial the number. Dial and say the number. For example, 12 consists of 1 tens and 2 ones.

3, skillfully recite the formula of carry addition and subtraction within 20.

20+ formula

92 1 1 83 1 1 74 1 1 65 1.

Jiu San 128412Wuqi12Erliu12

94 13 85 13 76 13

Ninth Five-Year Plan 148614erqi14

96 15 87 15

97 16 two 8

98 17

Two nines 18

(Two unified multiplication formulas of Jiujiu 18 are used instead of Jiujiu 18)

note:

1, the first two Chinese characters are addend, followed by Arabic numerals for sum, so that we can distinguish which is addend and which is sum;

2. The formula of addition is that the large number comes first and the decimal number comes last (such as 93 12), and the formula of multiplication is that the decimal number comes first and the large number comes last (such as 9327);

3. Don't let children count up by hand index or fixed addend, which will make it difficult for children to get used to it. The addition formula within 10 and the carry addition formula within 20 are just back, back and back. Practice makes perfect. Combined with some regular explanations, children's computing ability can be improved.

4. Reciting time can be arbitrary, and you don't need to spend a lot of time reciting. You can carry it on the way to pick up the children from school every day.

5. Be sure to practice export calculation every day, with 30 questions a day.

Subtraction of abdication within 20

The abdication subtraction within 20 is opposite to the carry addition within 20, that is, the abdication subtraction within 20 is converted into the addition within 10. The formula is: "Minus nine and add.

One, minus eight plus.

Two minus seven plus.

Three, minus six plus.

Four, minus five, plus five. "How to use the formula? Take "minus nine plus one" as an example. " Minus nine plus one "refers to a number MINUS nine, and the result of adding 1 to this number is their difference."

For example, 17-9 = () take the 7th place of 17, and add 1, and the result is 8, that is, 17-9 = 8, 13-9 = () take/kloc-.

Minus eight plus two, seven plus three, six plus four, five plus five equals minus nine plus one.

A Brief Comment on Primary School Mathematics Teachers

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The teacher is not at school, so the composition is urgent, urgent, urgent, urgent! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

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