Designer and Instructor: Baoshan 070 Nie Tiantian
Teaching content: the second volume of the fourth grade mathematics textbook published by People's Education Press, page 17, page 18.
Teaching material analysis:
Additive commutative law's Law of Harmony is the content of the lesson "Addition Algorithm" 1 published by People's Education Publishing House. Addition is one of the most basic operations in mathematics. From the vertical connection of textbooks, students learn the calculation method of addition. On this basis, through the teaching of this class, first of all, students' understanding of addition can be improved from perceptual to rational. It lays a good foundation for learning simple methods of addition in the future, and also lays a foundation for learning decimal and fractional addition in the future. Secondly, the text expression and letter form of additive commutative law's law of association are summarized by incomplete induction, which not only improves the abstract generalization of knowledge, but also lays a preliminary foundation for expressing numbers in letter form in the future.
Analysis of learning situation:
The fourth-grade students in my class have a good knowledge of addition. During the epidemic holiday, the whole province does not implement webcasting classroom teaching, but only carries out simple preview, so I have sent it to parents during the holiday to let the children have a preliminary preview. In teaching, I will focus on guiding students to consolidate their understanding and express additive commutative law and the law of addition in letters.
Teaching objectives:
Knowledge and skills
1, through learning, make students understand and master additive commutative law, and use additive commutative law for simple calculation.
2, let students learn to use symbols or letters to represent additive commutative law.
Process and method:
Teaching through observation, comparison and induction.
Emotional attitudes and values:
Cultivate students' abstract generalization ability and language expression ability, and guide students to rise from perceptual knowledge to certain rational knowledge.
Emphasis and difficulty in teaching:
Teaching emphasis: Make students understand and master the associative law of additive commutative law and addition, and express additive commutative law and associative law with letters.
Teaching difficulties: Make students experience the process of exploring additive commutative law and associative law, and discover and summarize the operation rules.
Teaching methods:
Autonomous cooperative inquiry learning strategy.
Teaching preparation:
Schiavo whiteboard courseware and onion mini-class: (1) additive commutative law (2) additive associative law.
Description of teaching time: during the epidemic holiday, it will be distributed to parents and given to children for preliminary preview, and classes will officially resume on May 6th.
Teaching process:
1. Play the onion micro-lesson "additive commutative law" and "Law of Additive Binding" in class.
1. Teacher: Students, just now we saw additive commutative law and the law of addition, and saw our "old friends" dog eggs, hammers and the king of triangles! What did you gain after reading it? Please tell me.
Students give examples to answer:
(1) I know what additive commutative law is.
(2) I will use letters to represent the laws of addition and association.
(3) I will use letters to represent additive commutative law.
Teacher: The students spoke very well! It seems that all students have gained a lot. Today, this class will follow the teacher into our mathematics kingdom. Let's explore the secrets of additive commutative law and the law of addition!
Second, create a situation
1. Interesting dialogue: How many students can ride bicycles in our class? Where did you ride the farthest? Cycling is a healthy exercise. No, there is an uncle Li riding a bike here!
2. Arouse a generation: (show the situation map)
Have a problem:
What information did you get from the situation map?
(2) What kind of problems should be solved?
The answer is preset: Uncle Li is known to ride 40km in the morning and 56km in the afternoon. The question is: Li Shu.
How many kilometers did Uncle Li ride today?
[Design Intention] Create interesting situations and let students feel the connection between mathematics and life. Review briefly before learning this lesson to arouse students' memory of previous knowledge.
Third, explore new knowledge.
1. Explore additive commutative law
Teacher: According to the information in the picture, how many kilometers did Uncle Li ride today? How to go public?
Students answer in columns, and the whole class communicates. Encourage students to say two different expressions and write them on the blackboard. )
40+56=96 56+40=96
(1) preliminary perception
What do these two expressions mean? Are the numbers equal? What symbol can be used to connect two formulas? Observing these two formulas, what do you find?
Blackboard: 40+56 = 56+40
Write on the blackboard according to the students' answers: guess-two addends exchange places, and the sum remains the same.
(2) Verify the conjecture
Lead: Is this conjecture correct? In order to verify whether our conjecture is correct, we can give more examples to verify it.
Students are divided into groups to verify and report. (requirement: everyone says a formula. )
(3) Lead to "additive commutative law"
Teacher: It seems that our guess is correct. The students are really good. Can you give this rule a name?
"additive commutative law".
Summary: two numbers are added, the position of the addend is exchanged, and the sum is unchanged.
[Design Intention] Let students experience the process of guessing and verifying, experience the happiness of success, change the boring memory way, and make students interested in mathematics learning.
2. Use letters to represent additive commutative law.
Teacher: We use Chinese characters to illustrate that additive commutative law is only understood by children in China. How can we show that it can be understood by children all over the world? Just try it. Use your favorite symbol to represent two addends, and use a formula to represent additive commutative law, so that students from other countries can understand it.
【 Design Intention 】 To further stimulate students' interest in learning, take students as the main body, and mobilize students' learning enthusiasm. On the one hand, it is conducive to the cultivation of symbolic sense and easy to remember; On the other hand, it improves the abstract generalization of knowledge and lays a preliminary foundation for the formal teaching of using letters to represent numbers in the future.
(1) Group discussion, class communication.
(2) Guide students to discuss: Experiencing letters can express "additive commutative law" more simply and clearly.
(3) Letter representation: A+B = B+A.
3. Explore the law of additive association
Teacher: The students in our class not only solved the problem, but also learned additive commutative law. So let's help uncle Li solve the second problem?
Teaching Example 2 (Showing Situational Diagram Courseware)
Show me the question:
What information did you get from the situation map?
(2) What kind of problems should we solve?
It is understood that Uncle Li rode 88km on the first day, and rode 104km on the second and third days.
96 kilometers. The question is: How many kilometers did Uncle Li ride in three days?
Follow-up: Can you list the comprehensive formula?
(3) How is the student exchange arranged? (Requirements: Use two different addition formulas to solve)
Formula: (88+ 104)+96?
Question: What do you count first? What else can be counted first?
Formula: 88+( 104+96)
(4) Comparing the two algorithms, what do you find? (Group communication)
(88+ 104)+96=88+( 104+96)
(5) Exercise: Can you fill in the following equation?
(69+ 176)+2869+( 176+28)
155+( 145+207)( 155+ 145)+207
Question: What laws do you find from the above equation?
Group discussion exchange report
[Design Intention] After the students got (28+17)+23 = 28+(17+23), I didn't ask the students to write such equations themselves, but showed several groups of equations with similar structures to guide them to think about whether these equations are equal through calculation. Find the law from it and get the law.
(6) Question: Is there such a rule in the addition of three numbers? Can you write more such equations? (living example)
(7) Summary: the law of addition and association: when three numbers are added, the first two numbers are added first, or the last two numbers are added first, and the sum is unchanged. Expressed in letters: (a+b)+c=a+(b+c)
【 Design Intention 】 On the basis of students' mathematical model conjecture, students are guided to write more formula groups with similar structures through analogical reasoning.
Fourth, consolidate practice and deepen understanding.
Using the practice of "classroom quiz" in onion micro-class, with the accumulation of gold coins and classroom optimization, Schiavo whiteboard classroom optimization master, students are highly motivated, experience the joy of harvest personally, consolidate knowledge, and further improve the flexibility of applying additive commutative law.
Verb (abbreviation for verb) evaluation and encouragement, and class summary.
What did you learn in this class? How do you feel?
[Design Intention] Summarize and evaluate in time, affirm students' little progress in the learning process, inspire and encourage them, and promote them to study more consciously.
Blackboard Design: additive commutative law? And association rule
40+56? =? 56+40 ? (88+ 104)+96=88+( 104+96)
? Letters indicate: a+b? =? b + a？ (a + b)？ +? c = a + ( b？ + c)
Teaching reflection:
In the teaching of mathematics, I got a preliminary understanding of onion college, where the micro-lessons are very vivid and helpful for understanding the knowledge. So I always wanted to share it with my classmates, so in April, I recorded two micro-lessons, additive commutative law and the law of additive association, and then shared them with my classmates. Combined with the students' preview feedback, I put additive commutative law and the law of additive association in one lesson. This class, I use onion micro-class to teach. Students pay close attention and watch the video attentively. The key points and difficulties in teaching can be solved through the onion animation micro-class, and the quizzes made by students are correct. In teaching, I use Schiavo whiteboard courseware, master of classroom optimization and other auxiliary teaching methods, so that students can consolidate the law of additive commutative law and addition and achieve ideal teaching results. Reflecting on this lesson, I have achieved the following:
1. Provide opportunities for independent exploration.
"Hands-on practice, independent exploration and cooperative communication are important ways to learn mathematics". In the process of exploring the law of addition, students are provided with time and space to explore independently, so that they can experience the process of the emergence and formation of the law of addition, gain successful experience in learning activities and enhance their confidence in learning mathematics.
2. Pay attention to students' existing knowledge and experience.
Pay attention to activating students' original knowledge and experience in teaching, so that students are always in the best state of actively exploring knowledge, and urge students to update, deepen, break through and surpass their original knowledge.
As a teacher for the first time, I still have many problems in teaching, such as insufficient guidance for students and single language for students' classroom evaluation. In the future, I will never forget your initiative, where I hope to take root and strive to become better! In addition, onion micro-teaching has been used for a long time. Every time after class, I will go into the classroom in advance to prepare the onion micro-class. Short animation teaching can explain the knowledge points of the whole class clearly, vividly and interestingly, which is very popular among students. If there is no onion class in any class, the students will ask me, "Teacher, why is there no onion in this class?" Gradually, the children have become accustomed to the company of the onion micro-class. It's really great for onion college! Thanks to the onion micro class and teachers! It would be better if there could be a micro-class of first-grade mathematics! After class, I also recommend the onion college to my colleagues, hoping that more people will use the onion micro-class. In the future, I will also make good use of it to assist teaching and make my math class more and more attractive.