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Knowledge points of second grade mathematics: three-digit addition and subtraction
Three-digit pen addition (the sum of the numbers on the same digit is equal to ten)

Non-carry addition

Carry addition

Continuous carry addition

Three-digit pen subtraction (number subtraction on the same digit returns 1 to 10)

Don't give up.

abdicate

Successive abdication

Solve practical problems in life:

Buy electrical appliances (oral addition and subtraction)

Knowledge points:

1, master the method of adding and subtracting integer hundred and integer ten, and can do oral calculation correctly.

2, can use the knowledge to solve practical problems.

Recycle waste batteries (three-digit pen addition)

Knowledge points:

1, can correctly calculate three-digit addition, step-by-step calculation, or direct vertical calculation of three numbers together.

2, can correctly estimate the three-digit addition.

3. Be able to use addition, addition and other knowledge to solve some simple practical problems, which can be formulated step by step or comprehensively.

Transporting Chinese cabbage (three-digit continuous subtraction)

Knowledge points:

1, can correctly calculate three-digit continuous subtraction, and calculate step by step.

2, can use the knowledge of continuous subtraction, solve some practical problems, can be step by step, can also be a comprehensive formula, some problems can be written directly (see pictures).

Buy a washing machine (three-digit addition and subtraction mixed operation)

Knowledge points:

1, can correctly calculate the addition, subtraction and mixing of three digits, and gradually get rid of the calculation.

2. Be able to use what you have learned to solve simple practical problems. You can make a step-by-step formula or a comprehensive formula.

Three-digit pen addition without carry addition. The numbers on the same number add up to ten equals one.

Carry addition

Continuous carry addition

Knowledge points:

Three-digit pen subtraction does not abdicate the number subtraction on the same number, and one is the back when the number is ten.

abdicate

Successive abdication

Solve practical problems in life

Three-digit addition and subtraction teaching plan

Teaching content:

P59—P60 Cases 3 and 4, Classroom Activities 1 and 2.

Teaching objectives:

1, we can find simple laws hidden in a given thing and apply them.

2. Cultivate students' spirit of independent thinking, active exploration and awareness of active cooperation with peers.

Teaching aid preparation:

Multimedia presenter, etc.

Teaching process:

First, the introduction of situations to stimulate interest

Do you like traveling, children? (Yes) Now let's go to Qiantang River to enjoy Tang Chao! (The courseware shows Qiantang River) What information have you learned from the picture just played? Qiantang bore is a natural phenomenon and a law. It is a gift from nature to mankind and the pride of our Chinese nation. There are many phenomena and laws like Qiantang River in nature and life. Do you want to appreciate and explore them?

Writing on the blackboard: exploring the law

Second, explore new knowledge.

I. Learning Example 3

1. In order to make the Qiantang River more beautiful and spectacular, people built a riverbank at Qiantangmen. Courseware shows fragments of riverbanks. What shapes of materials are they made of? (Square, rectangle)

2. Let the children take out six squares and put them on a pendulum to see what kind of riverbank you can put on. (Students do it by hand, teachers patrol and show students the figures)

Which paragraph do you like best? Tell me why.

4. The courseware shows the theme diagram of Example 3. Are they ordinary? What are the rules of these figures? How to draw the next picture? Tell me why.

5. Group Report: These figures all use six squares.

There is one more in the upper row and one less in the lower row.

Move from the next line to the previous line in turn.

Below 6, above 0; There are 5 below and1above; Four below, two above.

2. Research Example 4

1. There are many regular things in the mathematics kingdom. (The courseware takes the theme map of 4 as an example.) Please discuss in groups: What are the rules of these numbers? What number can I fill in? For what?

2. Student Report: The first number in each box is 5 more than the second number.

The second number in each group of squares is 5 less than the previous number.

The first number is 10, 15 and 20, increasing by 5 in turn; The second number is 5, 10, 15, 20, which also increases by 5 in turn.

The second number of the latter group is equal to the first number of the former group.

3. The children are really capable of finding the rules of figures and numbers through group cooperation. Now please complete the P60 question 1 independently.

Third, classroom activities:

Students do 1 and 2 questions, and then comment collectively.