1. Knowledge Objective: Combining with life situations and operational activities, students can initially know right angles, judge right angles, draw right angles with a triangle, initially know acute angles and obtuse angles, and know and judge these three angles.

2. Process and method: Through the whole activity, let students further understand the concept and characteristics of angles, establish the representation of three angles, find out the angles in life, and understand the close relationship between mathematics and life. Adopt the learning methods of observation and comparison, independent exploration, hands-on practice and cooperation and exchange.

3. Emotional attitude and values: let students feel the application of mathematics in life, stimulate students' interest in learning, and cultivate students' ability to operate, observe, compare and solve problems.

Emphasis and difficulty in teaching

Teaching emphasis: understanding, distinguishing right angle, acute angle and obtuse angle, deepening the understanding of right angle through overlapping, comparison and painting, and finding these three angles on the surface of objects.

Teaching difficulties: being able to judge right angles and draw right angles, and knowing that all right angles are big for each other.

teaching tool

ppt

teaching process

First, review the introduction of new lessons:

Students, we know the horn. Do you remember the names of the parts of the horn?

(Ask students to answer)

Second, learn new lessons.

1, know the right angle

Teacher: Last class, we got to know horns. We can find horns in many things in life. Today, the teacher gave

You brought some photos of your new friends. It is also a kind of figure called right angle.

Let's look at these figures. Is there a right angle hidden in it?

How many right angles does a square have? What about the rectangle?

Can you find more right angles in the classroom?

Can you draw a right angle with a piece of paper?

Teacher's demonstration: take out a piece of paper, fold it up and down, and fold it left and right.

Step 2 draw a right angle

The teacher demonstrated the steps and methods of drawing right angles. Finally, mark the right angle symbol.

3. Understand acute and obtuse angles

The following three objects all have right angles, and the angles are different. What do you find by comparing the right angles on the triangle ruler?

An angle smaller than a right angle is called an acute angle, and an angle larger than a right angle is called an obtuse angle. This is a preliminary understanding of the new content of right angle, acute angle and obtuse angle we are learning today.

Who is the elder brother and who is the younger brother? (in descending order)

4. Angle of demonstration activities

The teacher took out the activity angle and asked the students to rotate both sides of the angle to make it a right angle, an acute angle and an obtuse angle respectively.

Third, consolidate the practice.

1. Can you name the following corners quickly? Courseware display

2. Who is smart and who will guess? (Courseware demonstration)

3. Calculation Angle (courseware display)

What did you buy today?

Fourth, homework

The textbook has 44 pages, exercise 8, title 1 1, 12.