Teaching objectives:

1, master a slightly more complicated solution with more than one number;

2. Further understand the relationship between the percentage application problem and the corresponding score application problem;

3. Enhance the awareness of application and realize the application of percentage in real life;

4. Improve students' ability of analogy, analysis and problem solving.

Teaching emphases and difficulties:

Find the unit "1" and master the solution to the problem of how many numbers are more than numbers.

First, review the old knowledge, review the groundwork

( 1), 3/4× 42/3 ÷ 2/3 1+ 12%

(2) What is 3/5 of 20? How much is 70% of 30?

(Design intention: Review the calculation method of "What is the fraction (percentage) of a number" and the related calculation of percentage, so as to pave the way for new knowledge. )

Second, teacher-student interaction, exploring new knowledge

(1) Ask questions independently and generate questions.

1. Teacher's oral information: the school library has 1400 books, which has increased by 12% this year.

2. Retell the information you just heard.

(Design intention: cultivate students' memory ability and good habit of listening to lectures. )

3. Students ask relevant percentage questions and introduce examples.

Default question: ① How many volumes have been added? 2. How many books are there this year? (3) What percentage of books are there this year?

(Design intention: Brainstorming questions put students in the main position of learning, which not only cultivated students' problem consciousness, but also fully mobilized students' attention to the classroom, paving the way for later teaching. )

(2) solving problems, giving examples.

1, example 3:

Teacher's statement: Add the information just now and the second question raised by the students, that is, Example 3 we are going to learn today.

Example 3: The collection of books in the school library is 1400 volumes, which has increased by 12% this year. How many books are there now?

2. Analyze the quantitative relationship and determine the method to solve the problem.

(1), focusing on guiding and analyzing "the number of books increased this year 12%".

Guidance: What does the increase in the number of books and albums 12% mean this year? Have you seen similar problems there? Would you solve it if you changed 12% into the number of components? We can solve the problem of percentage application by solving the problem of score application. What is the equivalence relation? (Number of books this year = number of original books+number of books added) What is the unit "1"? What shall we ask first? (that is, the question 1) What do you need to increase the number of books? How to go public? (1400× 12%) The teacher taught a calculation method of multiplying a number by a percentage. )

(Design intention: Review the old knowledge, introduce the new with the old, and let the students literally understand the meaning of "the number of books increased this year 12%" with the help of the ideas and methods of solving fractional application problems, pay attention to the transfer and analogy of knowledge, learn the problem-solving methods, give students a space to explore and experience the formation process of knowledge. )

(2) According to the equivalence relation expression, the integrity of the process is emphasized.

(Design intention: According to students' reality, let students learn some calculation methods and skills, and cultivate students' good thinking habits and study habits. )

(3) Draw students to talk about the meaning of the formula, review the thinking of solving problems and talk about the main points of solving problems. (Find the unit "1" and its equivalent relationship. )

(Design intention: Let students learn the ideas and methods of solving problems by reviewing the ideas of solving problems. )