Tisch
Teaching objectives
1. Explore and understand the meaning of the score multiplied by the score according to the specific situation;
2. Explore and master the calculation method of fractional multiplication and calculate it correctly;
3. Can solve the simple practical problems of fractional multiplication and experience the close relationship between mathematics and life.
Training points for education and training:
Teaching emphases and difficulties
1. Explore and understand the meaning of the score multiplied by the score according to the specific situation;
2. Explore and master the calculation method of fractional multiplication and calculate it correctly;
Teaching preparation:
1. Each person should prepare a piece of paper with a length of10cm;
Everyone prepares five rectangular pieces of paper.
Teaching process:
Firstly, the significance and calculation method of fractional multiplication are discussed.
1. Let the students read a paragraph on page 7 of the textbook first. Then let the students take out a piece of paper prepared before class and cut it according to the example.
After cutting, the teacher asked: How to find out "how much money is left in this note?"
And write the number according to the result of cutting.
1/2× 1/2= 1/4 1/4× 1/2= 1/8
After the students listed the formulas, the teacher asked: Why use multiplication?
Guide the students to understand that finding the rest of the score on this paper means finding the score of 1/2, which is the same as finding the score of a number in the last class, so we use multiplication to calculate it.
Ten percent off, draw 3/4× 1/4-=?
Ask the students to take out a rectangular piece of paper prepared before class, fold it according to the requirements of the textbook and color it.
Discussion: (1) Please say, how much does the red part occupy the diagonal part? How many parts are there in the whole paper?
(2) Can you draw 1/4 first, and then draw 3/4 of 1/4?
Do: Fold, think and work out the result as above.
2/3× 1/5 5/6× 1/3
Say, can you summarize the calculation method of score and score multiplication?
Summary: Fraction multiplied by fraction, numerator and numerator product is numerator, denominator and denominator product is denominator.
Think about it: Is there any contradiction between this method and the method of multiplying fractions by integers?
Give it a try:
1/4× 2/3 3/52/9 7/8×5/ 14
Emphasis: Give in first if you can.
Second, classroom exercises
1. Calculation exercise.
Page 8 of the textbook "Practice" Question 2.
Students observe after calculation: Is the product of fractional multiplication necessarily smaller than each multiplier?
Solve the problem.
(1) Textbook 8-9 "Practice" Questions 3, 4, 5, 6 and 7.
After the students finish speaking, talk about the ways to solve the problem.
(2) The mathematical story "Tang Priest Divides the Melon" on page 9 of the textbook.
Blackboard design:
Fractional multiplication (3)
Arithmetic of fractional multiplication: numerator multiplication, denominator multiplication, divisible divisor.
extreme
Teaching content:
Textbook "Fractional Multiplication" Page 7-9 (3)
Teaching objectives:
1. Through students' hands-on operation, with the help of graphic language, understand the meaning and algorithm of fractional multiplication, master the calculation method and be skilled in calculation;
2. Let students experience the process of guessing and verifying, and experience the methods of mathematical research;
3. Cultivate logical reasoning ability and infiltrate certain mathematical thinking methods.
Teaching emphases and difficulties:
Students can skillfully calculate the result of multiplying scores by scores.
Teaching process:
First, create situations, stimulate interest and expose topics.
1. Exhibition of China's ancient philosophical works.
Show review questions
3×2/5 4/5×2
3. Conveniently introduce a new lesson: fractional multiplication (3)
Second, the combination of support and release to explore new knowledge
1. Draw pictures to guide students to understand 1/2* 1/2.
2. Show 3/4* 1/4 to guide students to verify the above calculation method and rock reasoning process.
3. Display 2/3* 1/5, 5/6*2/3, write out the calculation process and summarize the calculation method:
Molecule times numerator, denominator times denominator.
Thirdly, feedback correction and implementation of double bases.
1. Show page 8 of the textbook and try 1-3.
2. Guide students to discover the law.
Fourth, summarize and evaluate the layout preview
1. Guide students to summarize in class.
2. Layout preview: Practice on page 10- 1 1 in the textbook.
Blackboard design:
Fractional multiplication (3)
Meaning: What is the score of a number?
Calculation rules: numerator multiplied by numerator, denominator multiplied by denominator.
Tisso
Teaching objectives:
1. Ability goal: Explore relevant mathematical information according to the needs of solving problems and develop the initial ability of fractional multiplication.
2. Knowledge goal: By learning the calculation method of score multiplication, students can skillfully and accurately calculate the result of multiplying one score by another.
3. Emotional goal: let students feel the close connection between fractional multiplication and life, and cultivate a good interest in learning mathematics.
Teaching emphases and difficulties:
Students can skillfully calculate the result of multiplying scores by scores.
Teaching methods:
Teachers and students are the same in induction and reasoning.
Teaching preparation:
Teaching reference books and textbooks
Teaching process:
First, check the import.
The teacher shows the teaching blackboard and asks the students to calculate the following fractional multiplication problems.
3/ 1 1×3 9/ 16× 12 2 1×5/ 14
Teacher: Go back and forth to patrol the students' questions and ask them how to calculate.
After the search, the students raised their hands to answer questions.
The teacher asked the students to answer the questions. (Integer multiplied by fraction, integer multiplied by numerator, denominator unchanged. Pay attention to two restoration methods. )
Second, teach new lessons.
The teacher showed the textbook example: a rectangular piece of paper, cut off its 1/2 for the first time, and cut off the remaining 1/2 for the second time. At this point, what is the rest of this paper money? If you cut off the remaining 1/2 for the third time, how much does the remaining part account for this paper?
The teacher asked the students to think about this example and ask questions.
1/2× 1/2? Analyze the first cut of 1/2 and the second cut of the remaining 1/2, that is, 1/2. That is 1/2× 1/2.
The teacher asked the students to see 1/4 from the picture, let them think from1/2×1/2 =1/4, and let them discuss at the same table.
The teacher asked the students to talk about the arithmetic of multiplying fractions by fractions. And encourage students' opinions.
The teacher and the whole class summed up the arithmetic of multiplying fractions by fractions: fractions multiplied by fractions, numerator multiplied by numerator, denominator multiplied by denominator as denominator.
Verification rules: let students origami to verify 3/4× 1/4? Ask the students to analyze the reasons.
Class discussion: Let the students say, according to the illustration on page 7 of the textbook, what is the ratio of the red part to the diagonal part? How many parts are there in the whole paper? Let students further understand the relationship between the whole and the part; What is the initial understanding of the score?
Third, consolidate the practice.
Try to make an 8-page textbook,1/4× 2/3; 3/5×2/9; 7/8×5/ 14
Students are required to calculate by multiplying scores by scores. Note the first reducible point, such as 7/8× 14/ 15 and 7 in 14.
Fourth, class summary.
Students, what knowledge have you learned in this class? (Ask students to answer)
Blackboard design:
Fractional multiplication (3)
1/2× 1/2= 1/4; 1/2× 1/2= 1× 1/2×2= 1/4
Arithmetic of fractional multiplication: numerator multiplication, denominator multiplication, divisible divisor.