The teaching plan of "Understanding of Circle" in the first volume of sixth grade mathematics
Teaching content:
Hebei education printing plate sixth grade mathematics first volume unit 1 first class hour
Teaching objectives:
Knowledge goal: draw a picture, fold it, observe and experience the characteristics of the circle, and organize students to know the names of each part of the circle.
Understand the relationship between the inner diameter and radius of the same circle.
Ability goal: let students know the relationship between diameter and radius and find out the symmetry axis of the circle.
Change students' learning style, cultivate students' thinking abilities such as observation, analysis and generalization, as well as the preliminary concept of space. Moral education goal: let students form the habit of acquiring new knowledge through communication and cooperation.
Teaching focus:
Explore the names, characteristics and relationships of each part of a circle.
Teaching difficulties:
Experience the characteristics of the circle through hands-on operation.
Teaching process:
(1) Scenario introduction
Show the scene map of the textbook, the car designed by animals, and think about the problem of Dr. Rabbit.
Student answers
Teacher: Have you ever wondered why wheels should be round? Where is the axle installed? Why? Answer.
Teacher: It's all related to the knowledge of the circle. In this lesson, let's get to know the circle (blackboard writing: understanding of the circle).
(2) Explore new knowledge
1, Teacher: Tell me where you can see the circle in your life.
Health: Some clock faces are round, buttons are round, coins are round, and balls are three-dimensional figures. The cross section obtained by cutting the ball in the middle is round. A circle is also a plane figure. )
Teacher: In life, circles are everywhere. A mathematician in ancient Greece once said that the circle is the most beautiful of all plane figures.
2. Draw a circle on the paper with a bottle cap or cylinder and cut it out.
Students do it independently.
Fold it according to the method in the book and think about what you found.
Discuss in groups and express your opinions.
The teacher made a summary. It is clear that a circle is an axisymmetric figure with numerous symmetry axes, and the diameter and radius are also introduced. 4 think about the following questions.
(1) How many radii and diameters can a circle draw?
(2) Are the radii in the same circle all equal in length? What about the diameter?
(3) What is the relationship between the diameter and radius of the same circle?
What else did you find?
Teacher: Tell me about your group's findings?
Health report:
(1) The same circle can draw countless radii and diameters.
Teacher: Does anyone have a different opinion?
Health: No.
(Teacher writes on the blackboard: there are countless radii and countless diameters)
(2) Teacher: What else did you find?
Health: The radii are all equal, and the diameters are all equal.
Teacher: What is the radius of the circle you drew? Where are the other students? What about the students who measure the diameter? Do you have a different opinion?
Teacher: Why are they not equal? To make the radii equal, a prerequisite must be added. (blackboard writing: same circle, same circle)
(blackboard writing: everyone is equal)
What else did you find?
Students report and teachers guide and summarize in time.
The diameter of the same circle is twice the radius, and the radius is half the diameter. Dialogue: Can you express their relationship in letters? (blackboard writing: d=2r, r=d? 2)
(4) The circle is an axisymmetric figure.
Teacher: Why? (Because circles can completely overlap after being folded in half)
Teacher: What is its symmetry axis? A straight line with a diameter is the symmetry axis of a circle. )
Teacher: How many symmetry axes does it have? (countless articles)
Third, classroom practice, consolidate and deepen.
Teacher: The students have a good command of it. Let's complete several challenges.
1, fill in the following table.
2 Judgment exercise, the whole class uses gestures to express their views together. Raise your hand correctly, but don't raise your hand wrongly.
(1) The diameter of a circle is twice the radius.
(2) Draw a circle with a diameter of 4 cm, and the distance between the two feet of the compass is 4 cm.
(3) A circle with a radius of 2 cm is larger than a circle with a diameter of 3 cm.
(4) All radii are equal.
(5) The line segment with two ends on the circle is called diameter 2. Draw a circle.
3. Interpretation and application
Why are wheels round? Where is the axle installed? Why?
Teacher: Why should the wheels be designed as circles instead of squares or other shapes?
When the wheel is made into a circle, the distance between each point on the wheel is equal to the radius of the wheel. When the wheel rolls on a plane, the distance between the center and the plane remains the same. Therefore, when the vehicle runs on a flat road, the rider will feel very stable, which is also the mathematical reason why the wheels are round.
Four: class is over.
Teacher: There is also a lot of beauty in mathematics. As long as you explore with your heart and are good at discovering, you can feel beauty.
Blackboard Design: Understanding of Circle
Within the radius of the same circle-equal, countless.
Middle diameter-equal, countless.
d=2rr=d/2
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