Teaching objectives:
1, by exploring the problem situation, students can get various methods to calculate 9 plus several on the basis of existing experience, and through comparison, students can experience relatively simple calculation methods; Make students understand the method of "adding up to ten", master the thinking process of carry addition of 9 plus several, and correctly calculate the oral calculation of 9 plus several.
2. Cultivate students' abilities of preliminary observation, comparison, abstraction, generalization and hands-on operation, as well as their abilities of preliminary asking and solving problems, so as to expand students' thinking and cultivate innovative consciousness.
3. Cultivate students' awareness of cooperative learning and mathematics learning, and promote the improvement of learning psychological level in learning.
Teaching emphases and difficulties:
Understand the thinking process of "adding ten methods"
Teaching aid preparation:
Courseware, two-color 18 stickers, verbal blackboard strips, small blackboard.
Learning aid preparation:
Dichromatic bar 18.
Teaching process:
First of all, stimulate interest and review basic knowledge.
Students, there is a sports meeting in our school today. Do you want to attend? If you want to participate, you must climb two wisdom mountains. Do you have the confidence to break through? (Yes)
Teacher: See which student can say the correct answer quickly, and you can climb the mountain quickly and take part in the sports meeting. Ok, let's start our little train!
(1), oral answer: 2 4 6 3 5
/ / / / /
1 () 1 () 1() 1() 1()
(2), oral calculation:
10+5 10+8 10+6 10+2
9+ 1+2 9+ 1+5 9+ 1+3
The students are so clever that they have successfully climbed two mountains. The sports meeting has already started. Let's go and have a look! (Show the scene map of the campus sports meeting)
(Design intention: Through the situation of mountain climbing game, let students feel that mathematics comes from life and is applied to life, which embodies the application value of mathematics, thus stimulating students' desire to explore. )
Second, try independently and explore the algorithm:
1, creating situations, teaching examples 1
(1) "Look, children, the game has started, and the playground is so lively (show courseware 1- theme map)! Please take a closer look. What's the game?
Health: Some people play badminton, some jump rope and some run.
(2) Teacher: The students really watched carefully. It is difficult for these athletes to participate in these competitions, so the children of the school service team prepared many delicious drinks for the athletes. (Show some drinks. Please take a closer look. What mathematical information did you find? What is the problem to be solved? (Name), say the name and let the students say it completely.
How to form? (Title on the blackboard: 9+4) Again, how did you know?
(On the basis of deskmate communication, report by name. Some students use the method of counting, some students use the method of next number, and some students use the method of rounding. )
(3) To sum up, the students really used their brains and came up with so many good methods. How clever you are! Which of these three methods do you like best?
(Design intention: Ask questions and solve them from the situation, so that students can initially feel the "ten-supplement method" and experience the "ten-supplement method" as a relatively simple calculation method. )
2, intuitive experience ten methods
(1) Teacher: Just now, some students knew how many boxes of drinks were in a * * * by counting, and some students got it through calculation. In fact, some students are smart enough to change the addition of 9 to the addition of 10 that we learned before. Let the students put the drinks in the box with sticks. Like a teacher, put 9 on the left and 4 on the right. (Set on the blackboard) Talk to each other about your thoughts at the same table.
(2) The teacher asked some students to speak in front.
(3) After the students pointed out in front, they asked: This little teacher is right. The teacher wants to test you. Why take one out of four? How about two people and three people? Oh, it adds up to 10, because 9 plus a few is 10, 9+ 1= 10. You are really good at thinking. Applause! )
(4) This method is called the Ten-Piece Method. Teachers and students say while demonstrating. The calculation process of filling ten on the blackboard. Teacher: 9+ score10 (raw 9+1=10). Divide 4 into 1 and 3,9+1=10, 10+3 = 65438.
(5) Now talk while posing as a teacher. The teacher checked the arrangement of the students.
(6) Students refer to the front. (including the process of pendulum and the calculation process of formula)
(Design intention: Through the operation, students can further form the representation of "rounding to ten", and then transform the representation into a schema and internalize it into a calculation method in time. )
Third, consolidate new knowledge and look for laws.
1, training to master the ten-point method.
(1) Students, you are great. You know 9+4, 9+5 teacher will definitely hit you. Put a stick in your hand, like a teacher, 9 on the left and 4 on the right, and talk as you put it. The teacher checked the arrangement of the students. Then put the stick aside and do the 1 question on page 89 of the book.
(2) Students fill in the blanks before pointing (small blackboard).
(3) Do the right side of the 1 question. (When answering the roll call, other students hold pens and judge for themselves to improve their attention. )
2. Cooperate to explore and deepen the ten-point method.
(1) Students, you are great. The teacher likes your performance very much. Let's start to do the second question. Do it seriously, and you will find something new.
Please close the book. Students, you are great. You like thinking so much that you can be called a little mathematician. It's amazing. Next, the teacher will test you little mathematicians to see who can solve the problems given by the teacher quickly and correctly, and tell me what you have found. Say its name.
3. Strengthen and consolidate the ten-point method.
(1) The students behaved so well that the teacher especially wanted to play the game of driving a train with you. You must have a train ticket to get on the train. If you want to play, finish the third question quickly.
(2) The game teacher had a good time. I want to play a guessing game with you. Do you want to play? "It is known that there are 9 small flowers. The teacher reported a dozen and asked the students to guess how many flowers the teacher had." Reward the students who answer correctly with a small red flower.
(Design intention: Through improving exercises, let students further consolidate and be proficient in the calculation of 9 plus several)
Fourth, the whole class summarizes and improves new knowledge.
What are the characteristics of the topic we are studying today? What did you gain from today's study?
(The teacher's summary ends here, without giving too many conclusive things or limiting students' algorithms. )
Instructional design of addition in 20 decimal places Part II I. teaching material analysis
This lesson is based on the fact that students have mastered the addition and subtraction of 6- 10. Therefore, I set the goal of this class closely around the suggestions elaborated in the new curriculum standard and combined with the three-dimensional goal.
Knowledge goal: stimulate students' interest in learning through interesting specific activities, and let students know the calculation method of 9 plus several in the activities.
Ability goal: it will be calculated by a decimal method.
Emotional goal: let students feel the fun and happiness of learning mathematics in the activities, so as to get a positive emotional experience.
According to the above objectives, I have determined the teaching focus of this class: I will use the method of supplementing ten to calculate.
Difficulties in teaching: the understanding and application of the ten-point method.
Second, teaching methods and learning methods.
According to the characteristics of teaching materials, I adopt the activity-based teaching method. Students construct new knowledge through a series of practical and practical activities, so that mathematics learning really becomes an interactive process between teachers and students. First-year students are lively and active, like new things and have a strong thirst for knowledge. In life, they have had an unconscious understanding of carry addition within 20 years. Therefore, in teaching, I strive to tap the learning resources around students and create a thinking space for them to discover and explore. At the same time, I also pay attention to cultivating students' evaluation ability, giving students opportunities for self-evaluation and mutual evaluation, and leaving the power of evaluation to students.
Third, the teaching process
According to students' autonomous cognitive rules and age characteristics, I use familiar objects throughout the class. I designed the following teaching links.
The first link: import from the game. The game is more suitable for the age characteristics of junior students. In this lesson, I introduced the game. The 9-person mixed group and 4-person mixed group of boys and girls counted the total number of the two groups. Ask the students to talk about how they worked it out (three calculation methods). Then through two games (9+6, 9+8) to demonstrate how to make up ten.
The second link: the combination of numbers and things, through a pendulum and a calculation, further experience the algorithm of the ten-point method. According to the age characteristics of junior students, they are active, so the calculation of numbers is transformed into: let students put a pendulum on the object to get the result, and then further understand the steps of the ten-point method in the process of pendulum. First, ask the students to arrange according to the formula, then move the objects to make up ten, and finally get the result. Let the students evaluate each other in the process of swinging.
The third link: the combination of numbers and shapes, through a circle, calculation and feeling algorithm. The cognition of junior students begins with observing intuitive objects. Intuitive thinking is dominant, and abstract thinking ability is in the development stage. Let the students combine figures and numbers, circle the figures to form ten, and calculate the results. Once again, I realized the process of supplementing the ten methods. It is also for students to evaluate each other, correct each other and learn from each other.
The fourth link: directly calculate the quantity without the participation of objects and graphics. This link requires students to get rid of dependence on objects and graphics. Will they still use the method of adding ten to calculate the result? First, let the students fill in the division of numbers. Second, the divided number and nine make up ten. Third, fill in the results.
The design of this lesson follows the age characteristics of students. Through games and hands-on activities, students can learn and move at the same time. Follow the cognitive characteristics of junior students, pay attention to thinking in images and develop students' abstract thinking at the same time.
The teaching design of addition in the base of 20 Part III The calculation part of this unit is divided into three sections, namely 9 plus several, 8, 7, 6 plus several, 5, 4, 3, 2 plus several. This arrangement reflects the repeated understanding process of learning knowledge and forming skills.
First, teaching materials
The arrangement of "using mathematics" in calculation requires students to discover mathematical problems through observation, collect information and data needed to solve problems, explore methods to solve problems, and obtain the whole process of solving problems.
Second, the teaching objectives:
1, let students skillfully calculate the carry addition within 20.
2. Let students learn to use addition and subtraction to solve simple problems.
3. Through mathematics learning, students can experience the close relationship between mathematics and daily life and feel the role of mathematics in daily life.
Third, the difficulties in teaching:
1, hands-on operation, let students understand and master the "add ten method" and find the law of carry addition within 20.
2, gradually abstract, prompting students to calculate numbers through thinking.
3. Ways to solve application problems with pictures and words.
Fourth, the application of teaching methods:
1, make full use of the theme map.
2. Let the students set up sticks.
3. Let students skillfully calculate with a verbal card.
Five, teaching methods:
1, independent inquiry, cooperative communication mode.
2. Observation and physical operation.
Six, teaching ideas:
9 plus a few
This textbook begins to teach oral arithmetic of carry addition within 20. The textbook is divided into two sections, the first section is the oral calculation of 9 plus several, and the second section is "using mathematics".
This part of the content can be taught in three classes. The content of teaching 9 plus a few can be arranged in 2 class hours, and mixed exercises of consolidation exercises can be carried out in class. To complete the exercise of exercise 17, you can arrange the content of "applying mathematics" in 1 class, do the addition and subtraction within 9 and 10 in class, and complete the exercise of exercise 18.
When teaching examples, there should be a panoramic wall chart and slide projection (courseware) of the sports meeting, and vivid game scenes should be described in language to attract students to "enter the stadium".
When teaching examples, let students pose by themselves and experience the process of ten addition in operation, so as to understand the arithmetic of carry addition and master the calculation method. For example, when calculating the acceleration of 9, ask students to put 9 red sticks on the left and 3 green sticks on the right, and then inspire students to think: 10 how to make up? You can play it several times more, so that students can form the appearance of making up ten in their minds, which can deepen students' understanding of the methods of making up ten and help them master it better.
What's eight, seven and six?
This part can be taught in 4 class hours. You can arrange the contents of teaching 8, 7 and 6 in two classes, and carry out consolidation and mixed exercises in the class to complete the exercises in exercise 19. You can arrange the content of "Applying Mathematics" in two classes, and practice the carry addition within 20 and the addition and subtraction within 10 in class to complete the exercise of Exercise 20.
When teaching example 1, on the basis of learning how to add several to nine, let students independently put out the process of adding eight to 10 with wooden sticks to deepen their perceptual understanding of the method of adding ten. On the basis of operation, let the students tell the oral calculation process of adding up 10 to calculate 8/5, which strengthens the understanding that if you add up to 10, you will divide another addend by 2 and several, which lays a good foundation for students to master the calculation method of 8 plus several.
Example 3 When teaching, let the students calculate 8 9 independently, and the teacher guides the students to say the calculation method.
Five, four, three, two plus a few.
These contents require students to complete these calculations with what they have learned. Page 1 10 of the textbook "Review" to review the carry addition problems learned earlier. Prepare to calculate the addend of 5, 4, 3 and 2 by the exchange addend method.
This part of the content can be taught in three classes, teaching 5, 4, 3, 2 plus several classes, and carrying out consolidation exercises and comprehensive exercises in class to complete the exercises in exercise 2 1.
Example 1 (on page 1 10), the picture of teacher's question 5 7=5 8= is attached below, which is intended to guide students to work out numbers with 75,85 and let them learn to exchange addends for calculation.
The example (page 1 10) only gives the formula. Ask the students to calculate the number of 4 83 9 with what they have learned, and consolidate the calculation of decimal addend with the exchange addend method.
Teaching design of addition within 20 decimal places Chapter IV Teaching objectives
1. On the basis of mastering the carry addition of 9, 8, 7 and 6, students can master the addition of 5, 4, 3 and 2 by transferring analogy.
2. Skillfully use the position of exchanging two addends to calculate the addends of 5, 4, 3 and 2.
3. Cultivate students' innovative consciousness and get diversified algorithms.
Teaching focus
Make students skillfully calculate the addition of 5, 4, 3 and 2.
Teaching difficulties
Make students master the calculation method of adding five, four, three and two.
Teaching preparation
multimedia courseware
teaching process
Modification and adjustment
First, dialogue import
The teacher showed me the oral arithmetic card.
9+5? 9+3? 8+5? 8+39+4
9+2? 8+4? 7+5? 6+66+8
7+6? 7+8? 9+6? 9+98+8
Look at the questions and choose one or two. Let the students say how they worked out the problem quickly.
Teacher: Everyone can use different methods to calculate the addition of 9, 8, 7 and 6. It's really good! Today we will continue to use these methods to learn how to add 5, 4, 3 and 2. (blackboard writing topic)
Second, explore new knowledge.
1, teaching example 4.
The teacher illustrated 1: 5+7 = □? 5+8=□4+8=□3+9=□, let the students calculate independently, and then talk about their own algorithms with their deskmates.
2. Question: How to say the numbers quickly?
Students report their own algorithms.
3. Teachers organize students to compare and realize that it is faster to calculate with the position of exchange addend.
Third, the feedback is perfect.
1, complete the "doing" question on page 95 of the textbook 1~3.
(1) Question 1 requires students to complete it independently.
(2) After the second question is divided into groups, the teacher guides the students to observe: each group of questions is up and down, with the big corner decimal above and the corresponding decimal increment below.
(3) Let the students finish the third question independently.
2. Complete the math game on page 95 of the textbook.
Teachers organize students to play games.
3. Complete the exercises on page 96 1 ~ 5 of the textbook.
Fourth, reflection and summary.
What have you gained from learning this lesson? What other questions are there?
Verb (abbreviation for verb) class assignment