People's Education Publishing House, Unit 5, Volume 11, Grade 6, Elementary School Mathematics, page 93, "Solving problems by percentage-how much is the percentage more (less) than a number".
Textbook analysis
Because of the relevant basis of fractional multiplication, we only try to find out how much a number is more than a number through Example 3, and other problems such as how much a number is and how much a number is less than a number are arranged in the exercises for students to try to solve.
Teaching objectives
1, through the students' independent problem-solving, master the basic method of finding more (less) percentage of a number;
2. Cultivate students' ability to analyze and solve problems by analogy.
Emphasis and difficulty in teaching
Teaching emphasis: how to solve the problem of how much (how little) a few percent;
Teaching difficulty: You can use the knowledge you have learned to flexibly solve a problem of more (less) percentage.
Teaching strategy
Using students' existing knowledge transfer analogy to solve the percentage problem.
Teaching course types
Briefing session; exhibition
teaching process
First, review the preparation.
1. Show the question: Find the unit "1" of the following question, and then write the equivalent relationship.
(1) A number is b number1/4;
(2) The number of A is more than that of B1/4;
(3)1/4 for a barrel of oil;
(4) The output increased by1/4;
2. Students think independently, communicate in groups, and tell the equivalent relationship of each small problem.
3. Show two application questions, and ask students to write the quantitative relationship before answering.
(1) There are 100 white rabbits, and only black rabbits belong to white rabbits. How many black rabbits are there?
(2) White rabbits 100, and the number of black rabbits is 50% of the number of white rabbits. How many black rabbits are there?
Design intention: review the quantitative relationship of fractional division to solve the problem of percentage. In addition, the important role of "1" unit is emphasized.
Second, impart new knowledge.
1, Example 3: There are 1400 books in the school library. Today, the number of books has increased by 12%. How many books are there in the library now?
2. Let students try to calculate boldly.
3. After the completion, ask the students to explain and tell the quantitative relationship.
(1) Method 1: Original album number+new album number = existing album number.
Format: Increase the number of books:1400×12% =168 (books).
Number of books now:1400+168 =1568 (books).
(2) Method 2: Original album number × (1+ 12%) = existing album number.
Formula:1400× (1+12%)
= 1400× 1 12%
= 1568 (volume)
4. Let the students talk about their feelings, and guide them to conclude that the problem-solving ideas of percentage application problems and fractional application problems are the same.
5. Summarize the idea of solving percentage application problems.
(1) 1. Find out the unit "1";
(2) Write the multiplication equivalence relation;
(3) labeling, which is solved in the column or column equation.
Design intention: I think students have a certain foundation in the previous study of "solving practical problems with percentages", so the study here is to let students try boldly, think independently and get solutions to problems.
Third, consolidate practice.
1, fill in the blanks:
(1) Six (2) classes have 15 people to participate in the school winter sports meeting, of which only 40% participated in the field events and some participated. 20% people not only participate in track and field events, but some people; The rest only participate in track events, accounting for 80% of the participants.
(2) A chicken farm hatched 2,400 eggs, 5% of which were not hatched, only one chick was hatched.
Design intention: help students understand and master the learning content of this lesson through simple quantity.
2, complete the textbook page 93 "do" 1, 2 questions.
3, contact with reality, solve the problem.
(1) Gai Lou actually invested 3 million yuan, 600,000 yuan more than planned. What percentage is the actual investment more than planned?
(2) The distance between Party A and Party B is 120km. Xiaogang traveled 72 kilometers from Party A to Party B by bus. What is the percentage of the remaining distance?
(3) Dig a canal, 20% on the first day, 60% on the second day, leaving 320 meters to dig. How long is this canal?
Design intention: through the above exercises, help students understand and master the practical problems of solving related percentages.
Fourth, class summary.
The teacher asked: Students, what have you learned and gained in this class? (Students speak)
Fifth, blackboard design.