1. In this chapter, we learned about fractional division. Please recall how many kinds of fractional division there are.

(1) score divided by an integer, for example, 5/7 ÷ 5;

(2) Numbers divided by fractions include integers divided by fractions, such as 20 ÷ 4/5; And the fraction divided by the fraction, for example, 2/3 ÷ 6/7.

(3) Do the second question of "reviewing" on page 52.

2, the significance of fractional division

(1) Page 52 "Finishing and Reviewing" Title 1: What should I do if I rewrite this multiplication formula into two division formulas? (Instruct students to rewrite according to multiplication and division, and then ask students to fill in the rewritten formula in the book)

(2) Let the students talk about how to rewrite the problem into two fractional division formulas.

(3) What is the significance of fractional division? Let the students understand that fractional division and integer division have the same meaning, and they are both operations to find the other factor by knowing the product of two factors and one of them.

3, fractional division. computation rule

How to calculate the fraction of (1) divided by an integer? How to calculate a number divided by a fraction?

(2) Guide students to summarize the unified calculation rules of fractional division: dividing by a number (except 0) is equal to multiplying the reciprocal of this number.

(3) Complete the 2nd question of P52 "Arrangement and Review".

(4)P53 exercise 13, question 2.

Second, reasoning training.

1, boys account for 3/5 of the class, and girls account for () of the class.

2, a pile of coal, used up 4/7, and left ().

3. This year's output increased by 1/8 compared with last year, equivalent to last year's ().

Third, comparative training:

1, one-step fractional application problem

Uncle Zhang keeps 200 geese and 500 ducks. What are the numbers of geese and ducks?

Uncle Zhang keeps 200 geese, the number of which is 2/5 of that of ducks. How many geese does he have?

Uncle Zhang keeps 200 geese, and the number of ducks is 5/2 of the number of geese. How many ducks does he have?

(1) Compare similarities and differences.

Guide the students to make a comparison, so that they can clearly understand that the three application problems all contain the same quantitative relationship in structure, that is, the number of geese, the number of ducks, and the number of geese is a fraction of that of ducks; The difference is that both the known and the unknown have changed. In solving problems, it is necessary to find out who is the standard and correctly determine which quantity is used as the unit "1"; The difference is that it is necessary to determine which method to use according to known and unknown changes.

(2) After the comparison, students will write down the process of answering three questions in their exercise books.

2. Show the problem group:

The waterway from Shanghai to Hankou is1125km long. A ship has traveled three-fifths of the way from Shanghai to Hankou. How many kilometers is it from Hankou?

(2) A ship from Shanghai to Hankou is 450 kilometers away from Hankou. How many kilometers is the waterway from Shanghai to Hankou?

(1) Students draw line segments by themselves, analyze and answer.

(2) Comparison: What are the similarities and differences between the two questions? How do you analyze and tell?

3. Show the problem group:

① There are 8 buses in the parking lot, which are more than buses 1/6. How many cars are there?

② There are 8 buses in the parking lot. There are fewer buses than cars 1/7. How many cars are there?

③ There are 2/kloc-0 cars in the parking lot, and there are fewer buses than cars 1/7. How many buses are there?

④ There are 2 1 car in the parking lot. There are more cars than buses 1/6. How many buses are there?

(1) Students draw line segments independently, analyze and answer.

(2) Comparison: What are the similarities and differences between 1 and 2? What about questions 3 and 4? How do you analyze and tell?

(3) Is it regular to solve the slightly complicated application problem of fractional multiplication and division? What is the law?

Guide students to summarize:

Firstly, analyze the "rate-dividing sentence" to determine which quantity is the unit "1"?

Draw a line chart and find out the corresponding relationship between "quantity" and "rate"

3. Find the known unit "1" by multiplication and "1" by division or equation.