A divider is the division of two digits.
Grade subject: fourth grade mathematics
Course Type: Preview
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Master: Yao Dongmei
Name:
Unit teaching objective
：
(
1
) Let students learn to divide ten, hundred and ten by mouth (quotient).
(
2
) make students master the calculation method of dividing two or three digits by two digits.
(
three
Let students experience the process of exploration and understand the changing law of business.
(
four
) enable students to estimate the division according to the specific situation and explain the idea of estimation.
(
five
) enable students to use what they have learned to solve simple practical problems and feel the existence of mathematics.
The role in life.
Teaching focus
：
(
1
) master the calculation method of dividing two or three digits by two digits.
(
2
) master the trial and commercial law of "rounding".
Teaching difficulties
：
Master the method of "rounding" trial quotient.
Oral division of labor
Teaching content:
People's education edition, the first volume of four-year mathematics
Seventy-eight
—
80
Page example
1
And practice 13.
Teaching objectives:
1
Enable students to master the division of divisor into two digits on the basis of existing knowledge.
2
Students explore oral calculation methods by solving practical problems and practical activities.
Familiar with and master the oral calculation method of dividing by integer decimal.
three
Cultivate students' thinking habit of actively transmitting knowledge.
Teaching focus
Master the oral calculation method of dividing quotient into one digit by integer ten.
Teaching difficulties:
Cultivate students' good study habits of careful calculation.
Teaching process:
(1) Introduction and revelation of the situation:
Preparation questions:
1
、
20
、
50
、
120
、
150
How many tens are there?
2
Oral calculation, how to calculate?
60÷2 80÷4 90÷3 120÷6
three
Let the students look at the illustrations and dialogues in the textbook and make up an application problem completely.
Students speak freely: the national day is coming, and the school buys balloons and distributes them to all classes. use
80
individual
Balloons, one in each class.
20
First, how many classes can you assign?
four
Which student can list the formulas? (Student Form)
Teacher:
(of a formula) Is this formula different from what we learned before? A divisor is the division of two digits.
By the way, this is what we are going to learn in this class:
(blackboard title: divisor is two digits.
Oral division of labor)
Learning goal: learn to calculate the oral division with divisor of two digits.
Second, guide self-study.
Self-study guidance
Please read it carefully.
Seventy-eight
Page example
1
(
1
) content, thinking:
1
、
80
÷
20=
How to calculate? What else can I do? Tell me what you think.
2
Think about it:
83
÷
20
≈(
)
80
÷
19
≈(
)
, these two questions and examples.
Is there a difference in the question? Can you work it out with the estimation you have learned and the division you have just learned?
five
Minutes later, Bibi will see who separates the two digits with their mouths.
Third, students learn by themselves.
1
Students read books according to the guidance of self-study and teachers' inspection.
2
, check the self-study effect:
(
1
) display
79
Perform certain actions on the page:
(Fill in the book)
60
÷
20= 90
÷
30= 80
÷
40=
62
÷
20
≈
93
÷
30
≈
80
÷
38
≈
(
2
) Please do it independently.
79
Page example
1
(
2
) Yes.
120
Colorful flags, distributed to all classes.
30
Face, but
How many classes can I share?
(
three
) think about it:
122
÷
30
≈(
)
120
÷
28
≈(
)
(
four
) do it.
180
÷
30= 240
÷
40= 420
÷
60=
184
÷
30
≈
240
÷
37
≈
420
÷
58
≈
(
five
Students fill in the questions in the book.
Fourth, discuss the correction and analyze the cause of the error.
1
Students at the same table correct each other.
2
Reason for error in comment analysis: Answer the above questions by name.
Five, standard testing:
1
Exercise in the textbook 13
1
Title: Launch the "Win the Red Flag" Competition. Tell me more about you.
How do you calculate what you think?
2
Exercise in the textbook 13
four
Topic: estimation and oral calculation, the teacher displays the topic through the computer and grabs it.
Answer.
three
Independent textbook exercise 13
2
、
three
、
five
Title.
Sixth, class summary: tell me what you have learned? How to calculate?
Seven, attached to the blackboard:
Divider is the division of two digits.
80
÷
20=4
83
÷
20
≈
80
÷
20=4
80
÷
19
≈
80
÷
20=4
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