Part I: Design intention: Inefficient or ineffective problems often appear in the classroom now. This class is specially designed to improve the effectiveness of classroom questioning.
Teaching content:? Page 9 "Make a number", do it, exercise 2, questions 4 and 5.
Teaching objectives:
Knowledge and skills:? Find out the meaning of numbers. Can skillfully write numbers into fractions and percentages.
Answer the practical questions about scores correctly.
Process and method:? Through the calculation of percentage, we can further master the method to solve the percentage problem.
Emotional attitudes and values:? Feel the close connection between mathematics knowledge and life, and stimulate interest in learning.
Teaching focus:? Understanding of multiple
Teaching difficulty: it will solve the practical problems about percentage in life.
Teaching method and learning method: cooperation and exchange, guiding exploration
Teaching preparation: courseware
Teaching? Study? Pass? Cheng:
First, review and pave the way
Student: Last class, we learned that when shopping malls cut prices, they often sell them in the form of discounts. Let's look at these problems together. (Courseware demonstration)
1. The original price of a T-shirt is 80 yuan. How much will it cost if there is a 20% discount?
(Current price = original price × discount)
2. For a certain type of mobile phone, the original price is 1000 yuan, and the current price is 900 yuan. How much discount is it?
(Discount = current price ÷ original price)
Xiaoming bought a toy in a shopping mall, and the shopping mall stipulates that he can get a 60% discount with a discount card. Xiao Ming used a discount card to deposit it in 8.4 yuan. What is the original price of this toy?
(The original price is the unit "1", and the unit "1" is found by equation or division. )
(corresponding quantity ÷ corresponding score = unit "1).
Second, the scene import
1. (Show courseware) Students observe and say what new math knowledge you have found. (Health: Agricultural harvest is often expressed by "a number". Did the students notice similar news reports? (Student newspaper related reports)
Teacher: What do you want to know about grades? (1) What is a number? B, how to solve multiple problems? C. what does the score mean? D. What's the difference between percentages and those we have learned before? ) Teacher: Students have so many valuable questions worth studying. Please turn to page 9 of the book and teach yourself the above contents.
Ask interesting questions to stimulate students' initiative. In teaching, we can consciously ask some interesting questions according to the content of the textbook, create vivid and pleasant situations, make students feel novel, exciting, interesting and infatuated, thus attracting students' attention and thinking positively; Asking questions in this link stimulates students' initiative in learning.
Second, the new teaching
1, understand the meaning of numbers.
Fraction: it means that one number is a few tenths or ten percent of another number, commonly known as "a few percent"
(1) Just now, everyone talked about the development and changes of scores, so what do these "scores" mean? For example, increase production by "20%". what do you think?
(Students discuss and answer, and the teacher writes on the blackboard at will)
Scores? per cent
Twenty percent? Two tenths? 20%
(2) 90% = =? = = 85% =? = = ? = =
(3) Fill in the blanks: (first change it into a score and then rewrite it into a percentage)
Ten percent = ()? = ? ( ? )% 30% = ()? = ? ()% 45 = () = ()% 85 = () = ()%
On the other hand: 90% of a number is rewritten as (); 85% rewritten as a number is ().
(4) Fill in the form:
This year, the grain output of our province has increased by 20% compared with last year.
(5) What do the following scores mean?
The total number of imported cars this year is 20% lower than last year.
The number of tourists in Beijing this year has increased by 50% compared with last year.
Guide the students to discuss and answer.
2. Solve practical problems.
(1) Courseware display textbook Page 9 Example 2:
A factory used 3.5 million kwh of electricity last year and saved 25% this year. How many tens of thousands of kwh will be used this year?
(2) Guide students to analyze the topic and understand the meaning of the topic:
Compared with last year, 25% electricity was saved this year. In which quantity is "1"?
Find out the quantitative relationship.
Ask students to find out the unit "1" first, and then find out the quantitative relationship;
Electricity consumption this year = electricity consumption last year ×( 1-25%)
Electricity consumption this year = electricity consumption last year-electricity saved this year compared with last year.
Gradients make it difficult to ask questions. Some questions, because the difficulties are relatively concentrated, so the teacher should set a "ladder" for the students' thinking. The initial questions are relatively simple. After the students answer correctly, they will gradually deepen, generalize and abstract, divide and decompose the difficulties in teaching, and gradually achieve the expected purpose.
Students answer independently according to relational expressions and columns.
The whole class communicates. Q: Do you have any different solutions? Skillfully changing questions and cultivating students' creativity. A problem often has multiple perspectives, which can be viewed from different angles, which can broaden students' thinking and cultivate students' thinking ability and innovation ability. )
Method 1: 350×( 1-25%) Method 2: 350-350×25%.
=350×75% ? =350-350×0.25
=350×0.75 ? =350-87.5
=262.5 (ten thousand kilowatt hours) =262.5 (ten thousand kilowatt hours)
Third, practice consolidation (courseware demonstration)
1. Last year, Uncle Chen harvested 18600 Jin of corn, which was more than last year 15%. How many kilograms of corn did he collect this year? 2、 ? In 20 12, the number of outbound tourists in a city was 15000, an increase of 20% over the previous year. 20 1 1 What is the number of outbound tourists in this city?
3. A car company exported 1.3 million cars in February, up 30% from the previous month. How many cars did it export in January?
Fourth, the standard evaluation (students do answer sheets)
1. Do it on page 9.
2. Last semester, Wang Ling scored 75 points in math. With the help of the teacher and her continuous efforts, her math score has improved by 20% this semester. How many points did she improve? How many points can I get now?
Verb (abbreviation of verb) course summary
Students, what have you gained from today's study?
The questioning in this link enables students to master knowledge comprehensively, systematically and firmly and cultivate their abilities.
Distribution of intransitive verbs
1, Exercise 2, Question 4 and Question 5 are written in the exercise book.
2. Preview the contents of page 10.
Seven, blackboard design
per cent
Fraction means that one number is a few tenths of another number, which is often called "percentage"
Turn it into a number? Scores? per cent
Two tenths? 20%
Teaching design of score II: teaching objectives;
1, combined with specific things, experience the process of understanding "writing a book" and answer practical questions about "writing a book". .
2. Be curious about the problem of "Cheng Shu" and gain a successful experience of using existing knowledge to solve problems.
Teaching focus:
Understand the meaning of "writing a book".
Teaching difficulties:
Solve the practical problems about "writing a book".
Teaching process:
First, review.
1, fill in the blanks
(1) 60% off is 10 (), which is rewritten as a percentage ().
(2) A 60% discount is 10 (), which is rewritten as a percentage ().
(3) A 10% discount is (), which is rewritten as a percentage ().
The shop bought a pair of jeans with 56 yuan money, because the jeans there were 30% off. What is the original price of this pair of jeans?
Second, create situations and introduce new lessons.
Did the students hear the farmers say that "the rice yield in my family is 20% higher than last year" and "the cinnamon in my family is only 50% after drying"? What do they mean? Initially, the term related to percentage in commerce was "discount", while the term related to percentage in agriculture was "percentage". Infiltrate environmental education
Third, explore the experience
(a) into a number, that is, a number is a few tenths of another number, commonly known as "a few percent." For example, ten percent is one tenth, and if it is rewritten as a percentage, it is 10%.
1, let the students try to rewrite 20% and 35% into percentages.
2. Ask students to talk about other industries that use decimal knowledge besides agriculture.
3. Exercise: Rewrite the following percentages.
Twenty percent = ()%; Forty-five = ()%; 72% = ()%.
(B) Teaching Example 2
1. For example. A factory used 3.5 million kwh of electricity last year and saved 25% this year. How much electricity was used this year?
Ten thousand kwh?
2. Let the students read the questions and analyze the meaning of the questions. How to understand that this year saves 25% electricity compared with last year? In which quantity is "1"?
3. Students try to analyze and solve problems independently, and teachers go to the classroom to understand the situation and guide individual students with learning difficulties.
4. Understand that "saving electricity by 25%" means saving electricity by 25% compared with last year. Therefore, the formulas and solutions are listed according to the solution of a few percent of a number.
350×( 1-25%)=262.5 (ten thousand kwh)
Or guide students to enumerate.
350-350×25%=262.5 (10,000 kWh)
Fourth, consolidate practice.
1, 30% = ()%; 56% = ()%; Eighty three = ()%;
2. Do it on page 9.
Step 3 solve the problem
(1) Last year, the rice output of a township was 1500 tons. This year, due to weather disasters, rice production is only 85% of last year's. How many tons of rice is produced this year?
(2) Dinghushan received180,000 tourists in 20 13 years, an increase of 15% over 20 14 years. What is the cumulative number of tourists in 20 14 years? (Sort out the garbage when you go out to play)
(3) The number of students in our school in 20 13 was 820, which was 20% less than that in 20 12. What is the number of students in our school in 20 12?
(4) A shoe factory's annual output of 201/kloc-0 is 300,000 pairs, and the annual output of 20 1 1 increases 16%, and the annual output of 20 13 is higher than that of 20 12/kl.
Verb (abbreviation of verb) course summary
What did you gain from this class?
Teaching design of score 3: teaching goal;
1. Make students understand the meaning of number and discount, and the relationship between number and fraction and percentage; Can solve the application problem about fractions.
2. Improve students' ability to analyze and solve application problems, and develop students' thinking flexibility.
Key points and difficulties:
Understand the meaning of multiples and discounts; Understand the meaning of fractions, fractions and percentages.
Teaching process:
First, review preparation
1. Convert the following numbers into percentages.
Li Zhuang planted 50 hectares of wheat last year and 60 hectares this year. Compared with last year, what percentage of wheat is planted this year?
Xiaohua's family contracted a vegetable field the year before last, and collected 4 1.6 tons of cabbage, 25% more than the previous year. How many tons of cabbage were harvested last year?
The teacher said: agricultural harvest is sometimes expressed by scores. Today, we are going to learn the application of fractions.
Blackboard writing: percentage application problem
Second, learn new lessons.
1. Example of computer demonstration: the purchase price of each TV set in the mall is 1800 yuan, and the selling price is 20%. What's the price of each TV set?
2. The meaning of numbers.
Teacher: What are numbers? In the fifth grade, we learned that "a few percent" is a few tenths. For example, "10%" is one tenth, which is equivalent to 10%.
(1) oral answer
"Thirty percent" is ten (), rewritten as a percentage ().
"Thirty-five percent" is ten o'clock (), which is rewritten as a percentage ().
(2) 70%? 25%? How much is 50%?
What do you mean by adding 20% to the selling price? What should be the price first?
What else can I do? The students exchanged views on solving problems.
4. Give an example 2.
Cao Zhuang Township produced 374,000 kilograms of cotton last year. This year, due to insect pests, the output decreased by 15%. How many thousands kilograms of cotton will be produced this year?
(1) Students read the questions and understand the mathematical information in the questions.
(2) What does it mean to reduce production by 15%?
(3) Students answer independently and name students to talk about problem-solving ideas.
The teacher said: in column calculation, we can directly convert "into a number" into a percentage, and use the percentage to calculate the determinant.
Blackboard design:
37.4×( 1- 15%)
=37.4×0.85 =3 1.79 (ton)
A: This year's cotton output is 365,438+790,000 kilograms.