Teaching objectives:

1. Further understand the rotation of the graph, understand the meaning of rotating 90 clockwise or counterclockwise around the point, and draw the graph after rotating the simple graph 90 on the grid paper.

2. Through learning activities, further enhance students' concept of space and develop thinking in images.

3. In the process of understanding rotation, I am interested in graphic changes and further feel the application of rotation in life.

Teaching emphasis: master the three elements of graphic rotation.

Teaching difficulty: draw a simple figure after rotating 90 degrees clockwise or counterclockwise on square paper.

Teaching preparation: courseware

Teaching process:

First, situational import

1. Play the courseware about windmills and ferris wheels.

Question: What are the sports of the Ferris wheel and windmill in the playground?

Follow-up: Can you tell me how they rotate?

All around the middle point.

2. Introduce new courses.

What else do you want to know about rotation? Today we will continue to learn about rotation. (blackboard writing topic)

Second, communicate and enjoy.

1. Understand the meaning of rotating 90 clockwise or counterclockwise.

(1) Create a situation and ask questions.

Play courseware: video of various vehicles entering and leaving the toll station on an expressway. In order to maintain order, turnstiles were set up at the toll station.

Lead to the question: What actions does the rotating rod have in the picture? What are the similarities and differences between their actions?

(2) Simulate the operation and understand the meaning.

Cooperate at the same table, take out the moving angle to simulate the opening and closing of the rotating rod, and discuss the clockwise and counterclockwise rotation.

Combined with the demonstration and communication of learning tools, it is clear that the opening and closing of the rotating rod belongs to rotation.

Summary: clockwise rotation is the same as clockwise rotation, but counterclockwise rotation is the opposite. Turn the control lever counterclockwise when opening and clockwise when closing.

(3) In-depth discussion: Which point and which direction does the rotating rod rotate when opening and closing? How many degrees did it rotate?

Guide the students to think with the rotating bar diagram in Example 2.

Students observe the communication and draw the following conclusions: when the lever is opened, it rotates 90 clockwise around O; When the rotary lever is closed, it rotates 90 degrees counterclockwise around O.

(4) All activities to deepen understanding.

Listen to the command and do the action: let the students extend their right arm horizontally first, and use the action to indicate clockwise and counterclockwise rotation, and then extend their left arm horizontally once to experience clockwise and counterclockwise rotation for themselves.

2. Rotate the graphics on the grid paper.

(1) The courseware shows example 3 on page 3 of the textbook.

(2) Name: How to understand the requirements of the topic?

Guide students to examine questions: central point: point a; Rotation direction: counterclockwise; Rotation angle: 90.

(3) Hands-on operation.

Students use triangular pieces of paper prepared before class to rotate on square paper.

The teacher patrolled to understand the students' operation.

Name the students to make a rotating demonstration with physical projection, and encourage them to express different views.

(4) Draw the rotated figure on the square paper.

Question: If you don't use concrete objects, how can you draw the figure after the triangle rotates 90 counterclockwise? (Show the situation map at the top of page 4 of the textbook)

Students may have the following methods:

① First, rotate a right-angled side of the triangle 90 degrees counterclockwise around point A, then draw another line segment, and finally connect it into a corresponding figure.

② First, rotate the two right-angled sides of the triangle counterclockwise by 90 degrees around point A, and then connect them into corresponding figures.

(3) Turn and draw with the help of tools such as hands and pens.

Let the students try to draw on square paper.

(5) Organize communication.

Show the pictures drawn by the students by projection, and let the students talk about how to draw them.

(6) Teachers and students sum up the same.

Question: What should I pay attention to when spinning on square paper?

Guide students to draw a conclusion through communication: first find a line as a standard, and then follow the three steps of "fixed point, orientation and fixed angle"

Third, the feedback is perfect.

1. Complete the question 1 on page 4 of the textbook.

This problem is to consolidate the direction and angle of rotation with examples such as the hour hand of the clock face, the pointer of the platform scale and the pointer of the turntable. These exercises must not be treated rashly in teaching, they are all indispensable basic knowledge of rotating plane graphics.

Guide students to complete independently, answer questions by name and correct collectively.

2. Complete the second question of "Practice and Practice" on page 4 of the textbook.

This question is actually a supplement to Example 3. It rotates a rectangle 90 degrees clockwise around point A. Different requirements can be set for different students in teaching. For example, students with strong spatial imagination can draw a rectangle rotated by 90 directly on the grid paper; Students who have difficulty drawing directly can make a rectangle according to the appearance, rotate it on the grid paper according to the requirements of rotation, and then draw the rotated figure away from the real thing.

Fourth, reflection and summary.

What have you gained from learning this lesson? What other questions are there?