Unit 1-Multiplication and Division

course

title

How many small trees are there?

course content

Pages 2-3 of the textbook

Teaching objectives

1, knowledge and skills: explore and master the oral calculation methods of integer ten, integer hundred and integer thousand multiplied by one digit, and be able to perform oral calculation correctly.

2. Process and method: Combining with specific situations, in the process of discussing and solving practical problems, cultivate students' awareness and ability to ask and solve problems.

3. Emotion, attitude and values: further feel the connection between mathematics and life.

Emphasis and difficulty in teaching

Teaching focus:

Understand and master the oral calculation method of integer ten, integer hundred and integer thousand multiplied by one digit.

Teaching difficulties:

Master the oral calculation method of integer ten, integer hundred and integer thousand multiplied by one digit.

teaching process

First, review.

1, oral calculation.

7×8 = 9×6 = 6×5 = 8×5 = 4×6 =

How many tens are there in 270 100? How many hundreds are there in 500 and 2000 respectively? How many thousands are there in 4000?

3. What are four tens? 1 1 ten? How much is 500?1300? How much is 6 thousand?

Review the composition of numbers to prepare for oral calculation. )

Second, new funding.

1. Create a situation and ask questions.

(1) Guide students to observe the theme map first, understand the meaning of the map, and make clear how many bundles of trees there are in a * * *, and how many trees there are in each bundle.

(2) Guide students to ask questions, such as "How many small trees are there?"

(3) Students independently list formulas and answer them.

(4) Group communication.

2. Explore oral calculation methods.

In (1)20×3 =60, "20" means there are 20 trees in each bundle, "3" means there are 3 bundles, and "60" means there are 60 small trees.

(2) 20+20+20 = 20× 3 = 60 (you can swing with learning tools)

(3) Three 20 trees are six trees 10, which is equal to 60 trees.

(4) Because 2×3=6 and 20×3=60.

(5) It can also be understood that the calculation result can be obtained by writing another "0".

3. summary.

The meaning of 20×3 is the same as the meaning of multiplication in the table we have learned, which is a simple operation to find the sum of several identical addends.

4. Find a pattern. What did you find? )

2×3=6

20×3=60

200× 3 = 600 (200 times three is 600, which is 600).

2,000× 3 = 6,000 (2,000 times 3 is 6,000, which is 6,000).

Teacher: What are the characteristics of the formula we learned just now? These formulas are all a number multiplied by whole ten, whole hundred and whole thousand. )

Teacher: Do you have any good methods? (When a number is multiplied by integer ten, integer hundred and integer thousand, you can first calculate the product of the multiplier and the number before the zero of the multiplicand, then see how many zeros are at the end of the multiplicand, and add a few zeros at the end of the product. )

Thinking: asking questions → diversifying algorithms → establishing mathematical models → setting learning tools → discussing formula expression → analogical reasoning.

Third, give it a try.

Fourth, practice.

Look at the pictures and solve practical problems.

(1) Let the students understand the pictures and talk about the meaning of the scene. Find out how many bananas there are in each pile. Elephants and elephants eat several a day.

(2) solve the problem. Let students think independently first, try to solve problems, and then communicate.

Method 1: 60×3= 180 (root), and then calculate 200- 180 = 20 (root), which means it is enough for one day.

Method 2: 60×3= 180 (root), and then compare the size, because 180 is less than 200, so it is enough for one day.

(3) To solve the problem (2), first find out the condition that there are 7 days in a week.

(4) Solving problems (3) Because it is very important to cultivate students' questioning ability, we should ask questions from different angles.

Question 1: How many bananas are there?

Question 2: How many bananas do an elephant and a baby elephant eat every day?

Question 3: How many bananas did they eat in three days?

………………

Fifth, math games.

Stimulate students' interest in learning through lively math games and consolidate the oral calculation of multiplying whole ten by one digit.

Sixth, homework.

blackboard-writing design

How many small trees are there?

There are 20 small trees in each bundle, a total of three bundles. How many trees are there in a * *?

20×3=60 (tree)

A * * * has 60 trees.

Teaching postscript