Author and Work Unit Chai Kangcheng Feng Jingcun Town Primary and Secondary School in Luonan County

Textbook analysis

Example 1 teaches carry-free multiplication, which enables students to explore the calculation method of multiplying any two or three digits with a digit whose product per digit is less than ten on the basis of mastering the oral calculation of whole hundred and whole ten, and leads to the vertical writing format of multiplication. Through calculation, students know that multiplying any two or three numbers by a number is to multiply the numbers in each number by this number respectively, and then add the products.

Analysis of learning situation

Students have a sense of estimation. In teaching, let the students estimate first, then let each student try independently, then exchange their own algorithms in the group, and finally the whole class exchanges the representative algorithms of each group and discusses the solutions to the problems together.

Teaching objectives

Knowledge goal: to enable students to learn the vertical writing format of multiplication and understand the meaning of each step of vertical calculation.

Emotional goal: to cultivate students' spirit of cooperation and communication.

Ability goal: to cultivate students' writing ability.

Teaching emphases and difficulties

1, master the calculation method of multiplying two or three digits by one digit.

2. Understand the arithmetic of multiplying two or three digits by one digit.

teaching process

First, pre-school preparation: show oral cards.

6×2 4×2 20×3 40×2 300×2 20×4 50+7 6+40

Second, explore new knowledge.

1. Draw the situation diagram of 1, guide the students to say the meaning of the diagram, and put forward a problem to be solved by multiplication.

2, how to list, ask what to talk about.

3. Estimate the calculation results first.

4. How to work out an accurate result?

5. Report to the class.

Method one, put a small stick.

Method 2: continuous addition.

Method 3: Decomposition and combination.

6. Organize students to discuss the scope of application of these methods.

7. Guide students to use vertical calculation.

The teacher writes and explains on the blackboard.

12 The second factor should be aligned with the number of the first factor; Then 3 times 2, 1 one by one.

× 3

——————

six

3 0

——————

3 6

Further explanation: because the 3 on the tenth bit of the product represents three tens, this 0 can be omitted, and the 3 can be written directly on the tenth bit of the product. The teacher wrote on the blackboard again:

1 2 ... factor

× 3 ... factor

————

3 6 ... products

Ask the students to talk about the calculation process together.

Third, consolidate practice.

3 2 3 1 2 3

×2 × 2 × 2

______ ________ ________

After the students finish speaking, talk about the calculation process of the second and third questions.

Class assignment: textbook exercise 16 1-4.

Fifth, thinking training.

Saw a piece of wood 10 meter long into a short piece of wood 2 meters long. 3 points for each paragraph. How many points does it take to finish sawing it?