Second, the teaching objectives:
1, understand the meaning of decimals, and know that one decimal, two decimals and three decimals represent several tenths, several percent and several thousandths respectively. ...
2. Know that the progressive rate between the counting unit on each bit and two adjacent counting units is ten, and get a preliminary understanding of how many such units there are in each bit of a decimal part.
3. By understanding the generation and development process of decimals, we can improve our interest in mathematics learning and enhance our love for mathematics.
Third, teaching focuses on difficulties.
Key point: Understand the meaning of decimals.
Difficulty: Decimals will be used to represent the results of unit of measurement conversion.
Fourth, teaching preparation.
Multimedia, meter ruler.
Teaching process of verbs (abbreviation of verb)
(A) the introduction of new grants
Teacher: Where have you seen decimals in your life? Can you talk about it? (Show) Students answer.
Teacher: Decimals are used in so many places in life, which shows that decimals are widely used and everywhere. Please talk about the data of measuring the length, width (or height) of the surrounding objects. The teacher will divide the data into "whole meter number" and "non-whole meter number" on the blackboard. )
Teacher: If you still want to write these parts in meters, what numbers can you use besides scores? Please read the content on page 32 of the textbook.
Teachers and students have the same induction: when measuring and calculating, it is often impossible to get integer results, so it is often expressed in decimals. But what is the meaning of decimals? In this lesson, we continue to learn more about decimals.
Blackboard writing: the meaning of decimals.
(2) Exploration and discovery
1, know a decimal place.
(1) Show the example 1 meter scale map on page 32 of the textbook.
Divide 1 evenly into 10. How long is each part? 1 decimeter?
The teacher introduced and demonstrated that "one tenth" meter can also be written as 0. 1 meter.
What about 2 decimetres and 3 decimetres? Students try to fill in the blanks.
Students communicate in groups, and then the whole class communicates. When communicating, talk about the meaning of each score.
The teacher answers the blackboard according to the students' answers:
1 decimeter = meaning and nature of decimals in Unit 4 of PEP Mathematics for four years (1) m =0. 1 m, 3 decimeters = meaning and nature of decimals in Unit 4 of PEP Mathematics for four years (1) m = 0.3m. ...
(2) Observing the above equation, can you find the connection between fractions and decimals?
Students observe and discuss in groups.
Summary after communication between teachers and students: the denominator is 10, which can be written as a decimal. A decimal place represents a few tenths.
2. Know two or three decimal places.
We know that one digit after the decimal point represents a few tenths of a number, so what should two or three digits after the decimal point represent? Now, please take these two decimal places as materials and continue your research.
(1) The teacher continued to show the enlarged view of the meter ruler.
Students give feedback after thinking and group communication;
Divide 1 meter into 100 parts, and one or more parts of the meter represent a few percent, which can be expressed by two decimal places such as 0. 04 and 0.0 1.
1 meter has 1000 mm, that is to say, 1 meter is divided into 1000 copies on average, and 1 mm is the meaning and nature of the fourth unit decimal in the four-year (1) meter of mathematics published by New People's Education Press, which is 0.000 in decimal terms.
(2) summary.
The denominator is a fraction of 100, which can be written as two decimal places. Two decimal places represent a few percent.
The denominator is a fraction of 1000, which can be written as three decimal places. Three decimal places represent thousands.
3. The meaning of decimals.
The denominator is 10, 100, 1000 ... Such a score can be expressed in decimal. What are the units of these decimals? What is the forward speed between every two adjacent counting units?
Students talk about their understanding of decimals
Teachers and students * * * come to the conclusion that a decimal place means a few tenths, and the counting unit of a few tenths is one tenth, so the counting unit of a decimal place is 0. 1. Similarly, the counting unit of two decimal places and three decimal places is 0. 0 1 and 0.005438+0. The propulsion rate between every two adjacent counting units is 10.
4. Read "Do you know?" .
Teacher: Students already know how decimals are produced and what decimals mean. Do you know the history of decimals?
Page 33 of the self-study textbook for students "Do you know?" .
When communicating with teachers and students, let students talk about the development history of decimals.
(3) Consolidate differences
1. Guide students to complete the "doing" on page 33 of the textbook.
Let the students fill in independently, and when correcting collectively, let the students talk about how to express it with fractions and decimals.
2. Fill in the appropriate decimal places in the brackets.
The Significance and Nature of Decimals in Unit 4 of Four-year Mathematics of People's Education Press (1)
() Yuan () kg () cm
(4) Evaluation feedback
What did you learn from today's class?
Summary after communication between teachers and students: Knowing decimals, I know decimals are used to represent numbers of one tenth, one hundredth and one thousandth. I also know the counting unit of decimals, and I know that the progressive rate between adjacent counting units is 10.
(5) Blackboard design
The meaning of decimal
Fractions with denominators of 10, 100, 1000 ... can be expressed in decimals.
Decimals are counted in tenths, hundredths and thousandths ... Write 0. 1, 0.0 1, 0.00 1 ...
The propulsion rate between every two adjacent counting units is 10.
Six, teaching postscript