Teaching Design of "Preliminary Understanding of Decimals"
Teaching Content: Qingdao Edition Primary School Mathematics Experimental Textbook "Learning at Home ―― A Preliminary Understanding of Decimals", Volume 2, Grade 3.
Teaching objectives:
1, combined with the actual situation, so that students have a preliminary understanding of decimals, understand the meaning of decimals, and read and write decimals correctly.
2. Make students realize that mathematics comes from life, use it in life, and cultivate students' feelings of loving life and mathematics.
3. In the process of group cooperation, cultivate students' active learning attitude.
Teaching emphasis: make students know decimals initially and read and write decimals correctly.
Teaching difficulties: understanding the meaning of one and two decimal places.
Teaching preparation: courseware, meter ruler
Teaching process:
First, create scenarios to introduce new lessons.
Teacher: Mathematics is around us, and there is mathematics everywhere in our life. These days, the teacher investigated several things that students are very familiar with. Do you want to know the results of the teacher's survey?
Health: Yes!
Teacher: (courseware demonstration) Students, please observe the big screen carefully. Do you have any questions to ask?
The pencil-box is about 0.2m long and the Chinese book is about 0.0 1m thick.
The pencil is about 0. 15m long and the desk is 0.7m high.
Health 1: What's the difference between these figures and those learned before?
Health 2: Why are these numbers a bit?
How long is 3: 0.2 meters?
S4: The thickness of China's book is 0.0 1 meter. What is 0.0 1 meter?
How long is 5: 0. 15 meters?
...
Teacher: What are the differences between these figures and those learned before?
Health: These figures are a bit.
Teacher: We call a number with a dot in the middle a decimal number. Today, the teacher will walk into decimals with everyone, understand decimals and know decimals.
(Comments: Introducing familiar things from students can not only stimulate students' interest in learning, but more importantly, let students feel the wide application of decimals in daily life in a subtle way, and effectively stimulate students' desire to explore in combination with students' questions. )
Second, learn to read and write through experience.
(A), to master the decimal reading and writing
Teacher: Please observe carefully how many fractions are divided into decimals.
Student: Decimals are divided into three parts.
Teacher: Yes, the point in the middle is called decimal point, which is pronounced dot. The part before the decimal point is an integer part and the part after the decimal point is a decimal part.
Teacher: Students, would you like to try to read these decimals?
Student 1: 0. 1 Pronunciation: 0.1 (teacher writes on the blackboard)
Health 2: 0. 15 Pronunciation: 0. 15.
Health 3: 0. 15 should be 0. 15, not 0. 15.
Teacher: How do you know?
Health: My mother told me when I was shopping in the supermarket.
Teacher: You are really a child who loves to learn. What the students said is correct. The integer part should be read as an integer, and the decimal part should read only the number on each digit. So how do you pronounce 0. 15?
Health: You should read 0. 15. (Teacher writes on the blackboard)
Teacher: It's really good. How do you pronounce 18.438+08?
Student: Pronunciation: 188.
Teacher: Please read the text below the scene on page 66 of the math book carefully, and pay attention to reading the decimal correctly.
(Students read sentences)
Teacher: Students, how do you write these decimals?
Health: I want to write the integer part first, then the decimal point, and finally the decimal part.
Teacher: You are so clever. This writing is correct.
(Students practice writing a few decimals)
(In this link, the teacher is tolerant. First, let students have an intuitive understanding of decimals, and then have a solid and effective reading and writing. )
Third, focus on understanding the significance.
(2) Understand one decimal place.
Teacher: Just now, some students mentioned how long 0.2 meters is. Please try to compare the length of the chalk box with your gestures.
(Student gestures)
Teacher: The students' estimates are similar. If you want to know how long 0.2 meter is, let's first study how long 0. 1 meter is.
Please take out the meter ruler and find out 0. 1 meter in groups. Look carefully. What did you find?
Health 1: I found that 0. 1 meter is 1 decimeter.
Health 2: I thought 0. 1 meter was11meter.
Teacher: The students are right. Divide 1m into 10, 1 is 1 10m, that is, 0.1m. (Teacher writes on the blackboard)
Teacher: What about 0.2 meters?
Health 1:0.2 meters is 2 decimeters.
Born 2: 0.2 meters is 2- 10 meters.
Raw 3:0.2 or divide 1 m into 10, and take two of them.
Health 4:0.2 meters is two 0. 1 meter.
Teacher: The students' answers are very good.
Students explore what 0.3m and 0.5m mean. )
Teacher: So the height of the table is 0.7 meters. Do you know what this is?
Health: 0.7 meters is 7 decimeters and 7- 10 meters.
Teacher: Like 0. 1, 0.2, 0.3, 0.5, 0.7, their decimal parts are only 1 digit, which we call decimal.
Students, please look at a decimal. What is the relationship between decimals and fractions?
(group discussion)
Student (Summary): One digit after the decimal point represents a few tenths.
Students' understanding of decimals is not a blank sheet of paper. In teaching, we should make full use of students' generating resources, let students think and explore freely, and let students perceive, understand and master the meaning of decimals more deeply. )
(3) Understand two decimal places
Teacher: Just now, some students mentioned how long 0.0 1 meter is. Please use gestures to compare the thickness of Chinese books.
(Student gestures)
Teacher: Please look for it on the meter ruler.
(Students cooperate to find 0.0 1 m)
Health 1: I think 0.0 1 m is 1 cm.
Health 2: Divide one meter into 100 parts, and one part is 1- 100 meters, that is, 0.0 1 meter.
What is 0.02m, 0.03m, 0. 15m?
Teacher: Please observe these two decimal places carefully. What's new?
(Summary after group discussion)
Student: Teacher, I found that the denominator of both decimal parts is 100.
Health: I found that their denominator is 100, and their numerator is a number after the decimal point.
Student: Both decimal places represent percentages.
Teacher: The students' answers are wonderful! The students in our class not only like thinking, but also are good at summing up. The teacher admires you very much.
Teacher: Did you solve the problem through the study just now? If it is not solved, please put it in the problem pocket and we will continue to study it later.
Create an atmosphere of independent inquiry, cooperation and exchange, share their own and others' opinions, and let students experience the process of discovery, exploration and creation through listening, asking, guessing and summarizing. )
Fourth, consolidate practice and deepen improvement.
Teacher: We learned decimals today. Please think about it. Where have you seen or used decimals in your life?
Health 1: seen in the supermarket.
Health 2: On the price tag of clothes.
S3: Textbooks are priced in decimals.
Health 4: Decimals are sometimes used to measure height.
...
Guide students to find decimals from life, closely link mathematics knowledge with life and let students feel the life of mathematics.
Teacher: Do the students think they are doing well? (good! ) The teacher gave you several questions to test. Passing the teacher's three levels means that you have learned quite well.
Level 1: Please write 3 decimal places at will.
The second level: find friends.
The third level: fill in the blanks.
8 decimeter = () meter = () meter 1 meter 20 cm = () meter.
3 Angle = () yuan 1.65 yuan = () yuan () Angle () points.
0.96 yuan = () \ () yuan = () yuan 80 \100m = () m.
Students are not only interested in the form of breaking through obstacles, but also practice very seriously.
Verb (abbreviation of verb) course summary
What did you get from this lesson?
Sixth, extracurricular expansion.
After returning home, measure the height of the whole family, expressed in meters and decimals.
Let students realize that mathematics comes from life and is used in life. )
General comment: In this class, teachers pay attention to the close connection between mathematics and life, follow the law that knowledge comes from life, reflect the application value of mathematics, and stimulate students' interest in discovery, exploration and discussion, which has achieved good results. Specifically, there are two points:
1. Create life scenes to make math problems come alive.
From the beginning, the teacher of this course takes the practical application of decimals in life as the breakthrough point, and creates scenarios from the students' life experience and knowledge background to guide students to have positive experiences; After class, students are extended to measure the height of the whole family, so that students feel that what they have learned is not simple and boring mathematics, but very interesting and intimate. There are mathematics everywhere in life, which is driven by a strong living atmosphere.
2, independent inquiry, cooperation and exchange, so that students can experience the process of knowledge formation.
"Mathematics knowledge, ideas and methods must be recognized, understood and developed by students in practical activities, rather than relying solely on teachers' explanations. "According to this concept, teachers should proceed from the reality of students' cognitive laws and knowledge structure in teaching, and let students actively construct their own cognitive structure from intuition to abstraction through purposeful observation, operation, communication and discussion.