1, in the learning activities of counting and calculation, experienced the induction process of multiplication formula of 5.
2, memorize the multiplication formula of 5, and use the formula to calculate.
3. In the process of summing up the formula, let students learn to think methodically.
Teaching emphases and difficulties:
Focus: analyze the quantitative relationship of multiplication application questions and answer multiplication application questions.
Difficulties: Write the multiplication formula independently according to the graphic meaning, and compile the corresponding multiplication formula.
Teaching process:
First, check the import.
1. One person calculates the result according to the formula, and the other person tells the multiplication formula used.
3×3= 4× 1= 2×2= 2×4=
2×3= 3× 1= 1×2= 4×4=
People at the same table recite the multiplication formula of 1 ~ 4.
Second, new funding.
1. Introduce a new lesson
(1) Show the test questions: add 5 each time and fill in the blanks.
(2) Q: Every time you add 5, that is, the last cell is 1 5 more than the previous cell, and the first cell is 1 5. How many 5' s should you add to the following cells respectively?
(3) After the students answer, the teacher further strengthens how many fives there are in each box and writes down on the blackboard: 1 five, two fives, three fives, four fives and five fives.
Explore and discover
(1) learning formula: "15 choose 5" (mainly guided by teachers)
The teacher showed pictures of the five-star red flag (made into simple multimedia courseware or pictures) and asked: What do you see? (Guide the students to look at the picture and say: Five stars have five angles. )
The teacher further led the students to say that a five-star has five angles, namely15, and a multiplication formula can be listed: 5× 1=5. According to this multiplication formula, a multiplication formula can be worked out: a five is five.
(Teacher's blackboard writing: 5× 1=5, one is five)
(2) Learning formula: "25 10" (mainly guided by teachers)
The teacher took out two more five stars and asked, how many angles are there now? What are they?
How much are two fives? Who can list a multiplication formula according to this diagram and work out the corresponding multiplication formula?
(Teacher's blackboard writing: 5×2= 10 25 10)
Learning formulas: "35- 15", "45-20" and "55-25" (students explore independently)
The third, fourth and fifth multiplication formulas guide students to understand the meaning of the problem through discussion and use the analogy of knowledge transfer to write and fill in books independently.
Then the teacher shows the three stars in turn, and instructs the students to write the multiplication formula according to the pictures, find out the number of the formula from the prepared question list and form the corresponding formula.
The teacher wrote down three formulas and three multiplication formulas on the blackboard.
(3) Q: Look at these five formulas and five multiplication formulas. What are their characteristics?
(5) The multiplication formula * * * has five sentences. The first half of each formula represents several 5s, and the second half represents numbers. The difference between the numbers of two adjacent formulas is 5. When a number is multiplied by 5, the last digit of this number is always 5 or 0. )
Third, consolidate the practice.
1.
2.5×2+5= 5×3+5= 5×4+5=
5×3= 5×4= 5×5=
Q: What is the relationship between the upper and lower questions of this question?
(1. The result of the upper and lower questions is the same. The following question is easier to write than the last one.
Two 5s plus 1 5s is three 5s; Three 5s plus 1 5s is four 5s; Four five plus 1 five is five fives. )
Fourth, inductive questioning.
What did you gain from today's study? Is there a problem?
Four. Allocation (omitted)
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Textbook description:
This topic is selected from the second unit of the third volume of the compulsory education curriculum standard experimental textbook-multiplication formula (1). The students in this unit learned the multiplication formula of 1-4, and accumulated some experience in compiling multiplication formula, which laid the foundation for new lesson learning.
Design concept:
Review the multiplication formula of 1-4 before class and get familiar with the arrangement law of the formula; Then through organizing a series of activities such as counting fingers, let the students gradually compile the multiplication formula of 5 in this activity; Finally, consolidate and strengthen through related exercises.
Teaching objectives:
1, let students go through the compilation process of multiplication formula of 5 and understand the meaning of each formula;
2. Be able to skillfully use them for oral calculation and further improve your sense of numbers.
Teaching focus:
Master the multiplication formula of 5.
Teaching difficulties:
Understand the meaning of each formula.
Teaching preparation:
Dictation card
Teaching process:
First, review and introduce new ideas.
We have learned the multiplication formula of 1-4 before. Can you recite it all? Do you think they are easy to recite? Today, we will continue to learn multiplication formula in this class. Are you confident to learn well?
Second, explore new knowledge.
1, the teacher held out a hand and said, do you know how many fingers there are?
A: Five.
Teacher: Do you know how many fives these are? Can you write the corresponding multiplication formula?
Students: 1 5, and the multiplication formula is: 1×5=5 or 5× 1=5.
Teacher: Can you make a formula from these two formulas?
Name the students to report. Write on the blackboard according to the students' answers: 1 5 1×5=5 or 5× 1=5, one gets five.
The teacher held out two hands and said, Do you know how many there are? Can you write multiplication formula?
Report by name, two 5 2×5= 10 or 5×2= 10.
The students all say the formula: 25 10. According to the students' answers on the blackboard: two 5 2×5= 10 or 5×2= 10 25 10.
3. Formulas "35 15" and "4520"
Division; Just now, we have compiled the first two formulas. Can you make up the next two sentences with your fingers and your deskmate? Student activities, teachers interspersed with guidance.
Two people at the same table send representatives to report the exploration results, and then follow the students to report on the blackboard: 3 5 3×5= 15 or 5×3= 15 35 15, 4 5 4×5=20 or 5×4=20 4520.
4. Cooperative learning between teachers and students.
The teacher held out a hand, randomly asked two students to hold out their hands, and asked other students to count one * * *. How many fives were there?
Students report collectively and say the last formula collectively. According to the students' answers, write on the blackboard: 5 5 5×5=25 5 5 25.
5. Summary: We have just compiled all the multiplication formulas of 5 through our joint efforts. Do you think they are easy to compile? Can you recite it quickly?
Third, consolidate and strengthen, skilled application.
1, recite formulas, recite collectively, recite by name, recite in groups, recite by boys and girls together.
2. Memorize the formula skillfully and guide the students to find out the relationship between the sentences of the multiplication formula of 5. Which sentence is the easiest to remember and which sentence is the hardest to remember?
3, induction and finishing: the difference between the two sentences is 5, and the unit of product is 5 or 0; Five fifths are the easiest to remember, and five fifths are the most difficult to remember.
4. Complete the textbook 13 page "Think about it".
5. Complete questions 1 and 4 of "Thinking and Doing" on page 14. Look at the formula and say the formula.
6. recite the formula at the same table, one person recites the first half sentence and one person recites the second half sentence.
7. Contact life, solve practical problems, and complete questions 5 and 6 of "Thinking and Doing" on page 14.
Fourth, summarize the whole class and report what you have learned.
Dear students, what knowledge and new skills have we learned in this class? Can you tell your classmates and teachers?
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Teaching objectives: knowledge and skills objectives;
(1) enables students to intuitively know the origin and significance of the multiplication formula of 5 on the basis of mastering the meaning of multiplication.
(2) Memorize the multiplication formula of 5 for calculation.
(3) Cultivate students' abstract generalization ability and transfer analogy ability.
Process and method objectives:
(1) guides students to complete the compilation process of multiplication formula of 5.
(2) Guide students to find formula rules and the best memory methods.
Emotions, attitudes and values;
Experience the connection between mathematics and life, stimulate students' feelings of loving mathematics, and form a preliminary sense of application.
Teaching focus:
Understand the source of multiplication formula of 5 and experience the preparation process of multiplication formula of 5.
Teaching difficulties:
Memorize the multiplication formula of 5, and you can solve simple practical problems with the multiplication formula of 5.
Preparation of teaching AIDS and learning tools: the teaching process of sticks, blackboards and theme maps;
First, review and pave the way
1, students, we have learned some knowledge about multiplication before, and now the teacher will test you. Do you have confidence?
2. Show the small blackboard:
Rewrite the following formula into a multiplication formula.
4+4+4+4+4+4 8+8+8+8+8+8+8 6+6+6
Everyone commands well, but it is troublesome to work out the result, but the teacher can work out the result quickly. Believe it or not, try it! When playing games, students say a multiplication formula of a number multiplied by a number, and the teacher can tell the result in one second. In fact, the teacher used a magic weapon, (mysterious) multiplication formula and blackboard writing, which was also called "Jiujiuge" by our ancestors.
Second, explore new knowledge.
1, derivative formula.
How many fingers are there in a hand? In other words, how many fives is it? How to form?
Blackboard book:151× 5 = 5.5×1= 5.
If you make up a formula, it's "five out of five"
How many fingers are there in your hands? In other words, how many fives is it? Teachers and students make up formulas together, formulas.
2, try to make up the formula.
How many fingers are there in three hands? What about four hands? Where are the five hands?
(1) Let the students try to list the multiplication formulas and make them up.
(2) Group communication.
(3) Report: 3 55× 3 = 15, 3× 5 = 15355.
Four 5 5×4=20, 4×5=20 4520.
5 5 5×5=25 5525
3. Remember the formula.
(1) Read the formula together.
(2) Find a regular formula.
(3) Remember the password formula and disturb the order.
(4) Read ballads and recite formulas. Boys and girls have the same back, so do individuals.
Third, expand applications.
1, I can do it (exercise 10, question 3)
One five () two five ()
Three, five () four, five ()
Five-five ()
2. You must know (one formula says two formulas)
Three, five, fifteen, four, five, twenty.
25 15525
3. (Exercise 10, question 4)
Step 4 think about it
5× 1=( ) 5×2=( )
Formula () Formula ()
5×3=( ) 5×4=( )
Formula () Formula ()
5. Do it according to the textbook 5 1 page.
6. Do exercises 10, question 8.
7. improve the problem. Think about it: minute hand 1 minute? Walk two squares for a few minutes, walk three squares ... can you use the multiplication formula of 5?
Fourth, summary. Let the students talk about what they have learned in this class.