The teaching goal of mathematics angle measurement in seventh grade.
1, knowledge and skills
(1) In the real situation, know that angle is a basic geometric figure, understand the concept of angle, and learn the expression method of angle.
(2) Knowing the unit of measurement of an angle, such as degrees, minutes and seconds, we can perform simple conversion and angle calculation.
2. Process and method
Improve students' ability to look at pictures and learn to look at problems from the perspective of action changes.
3. Emotional attitudes and values
Experiencing mathematical activities from the perspective of understanding in real situations can help us feel the richness of the graphic world, enhance our aesthetic awareness and stimulate students' thirst for knowledge.
Key points, difficulties and key points
1, key point: an angle can be expressed in different ways, and angle conversion is the key point.
2. Difficulties: difficulties in expression and angle conversion.
3. Key: Learning to observe figures is the key to correctly representing angles.
training/teaching aid
Multimedia equipment, protractor, clock, pyramid.
teaching process
First, the introduction of new courses.
1. Watch the clock and the four pyramids.
Ask questions:
What graphic images do the hour hand, minute hand and pyramid of a clock give us? Please draw it.
Student activities: Think and draw independently, and then watch the teacher's demonstration.
Teacher's activity: demonstrate the formation process of angle with multimedia: a ray OA rotates around the end point O to the position of OB, and a plane figure-angle is obtained.
Blackboard: Corner.
Second, new funding.
1, the concept of angle
(1) Question:
From the above activities, can you know what shapes the corners are made of?
The student replied: Two rays.
(2) Definition of an angle: A graph composed of two rays with a common endpoint is called an angle, and this common endpoint is the vertex of the angle, and these two rays are the two sides of the angle (as shown in the figure below).
2. Representation of angles.
Student activities: Read the textbook 137 to understand the expression of angle.
Teacher's activity: explain the different representations of angles, focusing on the representation of a vertex with multiple angles.
Please use an appropriate method to represent each corner in the figure below.
Student activities: Please ask one student to practice on the blackboard, and the rest will practice independently.
Teacher activities: inspect students' practice, give evaluation and give positive evaluation to most students.
Student activities: read the thinking questions on page 138 of the textbook, communicate in groups and draw conclusions.
Teacher's activities: Participate in students' communication, demonstrate the formation process of straight corners and rounded corners with multimedia, inspire and guide students to explore problems and evaluate the results of students' discussion.
A: Straight corners and rounded corners are formed separately.
3. Angle measurement.
Teacher's activity: instruct students to read the textbook P 138, and explain the angle measurement method and the conversion of degrees, minutes and seconds.
Blackboard writing: 1 rounded corner = _ _ _ _ _, 1 flat angle = _ _ _ _ _,1= _ _ _ _',1'= _ _ _ _ _ ".
Student activity: Think and complete the blanks above.
Example: Divide a fillet into seven equal parts. How many degrees is each part (accurate to the minute)?
The teacher explained the calculation process.
Third, consolidate the practice.
1. Exercise on page 139 of the textbook.
2. Calculation: (1) 48 39'+67 41';
(2)90 -78 19′40″;
(3)22 30′×8; (4) 176 52′÷3.
This exercise is done by students independently. During the exercise, fully communicate with the group to solve the problems during the exercise. When the teacher makes a tour, he answers the students with learning difficulties in time and asks them to write on the blackboard before commenting.
3. Think about it: When the clock is at 5: 00 15, what is the angle between the hour hand and the minute hand?
Teacher-student interaction: Observe the position of the hour hand and minute hand at 5 o'clock (15). The teacher will guide and inspire students to learn the relationship between the minute hand angle and the hour hand angle when the hour hand turns to 15, and ask students to communicate in groups and get the correct answer.
Answer: 76.5.
Fourth, class summary.
Teacher-student interaction, complete the summary of this lesson:
1. What is an angle? What are the figures that make up an angle? How to present an angle?
2. This lesson also reviewed the plane and rounded corners. How to make these two angles?
3. What is the unit of measurement of angle? How did they transform?
Verb (abbreviation for verb) assignment
1. Exercise 4.3 on page 144 of the textbook 1, 2, 3, 4.
2. Choose the class assignment design.