Learning objectives:

1. With the help of practical operation and graphic language, understand the meaning and basic algorithm of dividing a number by a fraction.

2. Master a calculation method of dividing a number by a fraction and calculate it correctly.

Key points: Understand the meaning and basic arithmetic of dividing a number by a fraction.

Difficulties in learning: using the calculation method of fractional division to solve practical problems.

Learning content:

One, one point

There are four identical circular pieces of paper.

(1) How many copies can you divide into?

Draw a picture:

List:

(2) How many copies can be divided into per 1 copy?

Draw a picture:

List:

(3) Every 1/2 copies, how many copies can it be divided into?

Draw a picture:

List:

(4) Every 1/3 copies, how many copies can it be divided into?

Draw a picture:

List:

(5) Every 1/4 copies, how many copies can it be divided into?

Draw a picture:

List:

Second, draw a picture.

1. There is 1 2-meter-long rope.

(1) cut into sections 1/3m. How many segments can it be cut into?

Draw a picture:

List:

(2) If it is 2/3 meters long, how many sections can it be cut into?

Draw a picture:

List:

2.3/4 How many 1/8?

Draw a picture:

List:

Third, fill in and think about it.

Fill in ">" in the box. "<" or "=".

4÷ 1/2〇4×2、4÷ 1/3〇4×3、4÷ 1/4〇4×4

2÷ 1/3〇2×3、2÷2/3〇2×3/2、3/4÷ 1/8〇×8

What did you find? ()

Fourth, give it a try.

8÷6/75/ 12÷3

You can use "dividing by an integer (except zero) is equal to multiplying the reciprocal of this integer." And "dividing by a fraction is equal to multiplying the reciprocal of this fraction." Do these two pictures merge into one sentence?

()

Mathematics Courseware for Grade Five in Primary School Part II: Fractional Division II

Teaching objectives:

1, understand the meaning of dividing a fraction by an integer, master the calculation method of dividing a fraction by an integer, and calculate it correctly.

2. Cultivate students' practical ability and ability to find and solve problems through practical activities and independent inquiry.

3. Experience a sense of accomplishment through a series of "independent inquiry-drawing conclusions" to enhance students' self-confidence in learning mathematics.

Teaching focus:

Understand the meaning of fractional division and master the calculation method of fractional division by integer.

Teaching difficulties:

Deduction process of calculation rules for integer fractional division.

Teaching preparation:

Multimedia courseware, rectangular paper, etc.

Teaching process:

First, review the old knowledge and accumulate the foundation.

When reviewing, I arranged two exercises to arouse students' memory and pave the way for students to choose effective information from their original knowledge.

1, indicating the problem:

(1) What is reciprocal?

(2) Can you give some examples of reciprocity?

(3) How to find the reciprocal of a number?

2, show multimedia: smile naughty to buy sugar.

Question 1: They each bought two bags of sugar. How many bags of sugar did a * * * buy?

Question 2: These white sugars weigh 2 kilograms. How much does each bag of sugar weigh?

Question 3: If Xiaoxiao's family 15 eats a bag of sugar, how many kilograms do they eat on average every day?

Second, create a situation and understand the meaning.

Display multimedia: divide 4/7 of a piece of paper into 2 parts on average. How much is each part of this paper?

1. Use the prepared paper, divide the paper into 7 parts on average, then smear out 4 parts, then divide these 4 parts into 2 parts on average, and color 1 part. Finally, see how many parts are drawn on the whole paper.

2. Report

Third, make bold guesses.

Students understand how 2/7 is obtained by operation. So how should we calculate fractional division? Let the students guess the calculation method of fractional division boldly. According to the reasoning just now, students can easily get the calculation method of "the denominator is unchanged, and the numerator of dividend is divided by integer to get the numerator of quotient".

Fourth, explore again.

1, the students soon found that some formulas can't be calculated by the above conclusions, such as 4/7÷3, and the division of molecule 4 by 3 is infinite.

2. Let the students draw a little, and then let them communicate in groups.

3. The calculation method of fractional division is obtained: dividing by an integer (except zero) is equal to multiplying the reciprocal of this integer.

Blackboard: Fractional Division (2)

Dividing by an integer (except zero) is equal to multiplying the reciprocal of this integer.