First, the understanding angle 1. Characteristics of an angle: a vertex and two sides (straight)

2. The size of the angle is related to the size of both sides, and has nothing to do with the length of both sides.

3. The angle of painting:

(1) Fixed Vertex.

(2) Draw a straight line from this point.

(3) Draw another side (at right angles, aim at the drawn side with the right angle side and draw a line along the other right angle side).

Second, the classification of angles:

1, understanding right angles: the characteristics of right angles,

2. Know acute angle and obtuse angle: acute angle is less than right angle, and obtuse angle is greater than right angle.

3. You can judge the right angle, acute angle and obtuse angle with a triangular ruler: overlap the vertex of the right angle on the triangular ruler with the vertex of the compared angle, then overlap one side of the right angle on the triangular ruler with one side of the compared angle, and finally compare the other side of the right angle on the triangular ruler with the other side of the compared angle. This line is a right angle, the inside is an acute angle and the outside is an obtuse angle.

4. Draw right angles, acute angles and obtuse angles.

Teaching plan of "understanding of angle" in mathematics of grade two in second primary school

Teaching content: new curriculum standard test textbook, the first volume of grade two mathematics, page 39, example 1.

Teaching objectives:

1, combined with life situations and operational activities, to enable students to know the angle, know the names of various parts of the angle, and learn to draw the angle with a ruler.

2. Enrich students' intuitive understanding of diagonal and cultivate students' spatial concept.

3. Make students actively participate in the process of learning mathematics such as observation, operation and induction, and gain positive emotional experience in the learning process.

Teaching emphases and difficulties:

1, so that students can have a preliminary understanding of angles, know the names of various parts of angles, and learn to draw angles initially.

2. Initially learn to draw angles with a ruler to understand the size of the angle.

Teaching process:

First, import

1, map guessing game

Before class, let's play a guessing game to see what the number might be. (Teacher shows the picture)

Default: Health: Triangle.

The teacher asked: How did you guess?

The teacher shows another figure, revealing a corner for the students to guess.

Default: triangle, square, rectangle ...

The teacher asked: Then how can we guess these figures?

Step 2 reveal the topic

Teacher: It turns out that children guess according to the angle on the picture. In this lesson, we will walk into the world of horns together and get to know them! (blackboard writing: a preliminary understanding of the angle)

Second, cooperation and exchange, understanding the angle.

(1) Find a corner

Teacher: Actually, there are many corners hidden in the objects around us. Oh, class, this is a beautiful campus. Can you find the angle from these objects in the picture? (Show the courseware) Hold out your little finger. Where is the corner?

Perception angle

1, look! The triangular ruler in the teacher's hand in the picture became mine. Who wants to point out to the front where its corner is? (3 corners)

Please take out the prepared triangular ruler, and let's touch and point like just now and see what we find. Tell your deskmate what you found!

(exchange learning)

3. Report: Both sides of the corner are straight and the corner is sharp.

(3) Observation angle

1. Teacher Jiao in the picture just took them out separately. Please observe these corners and tell your deskmate what are the characteristics of these corners?

2. The characteristics of deskmate communication angle

3. Name of each part of the angle: the sharp part is called the vertex of the angle, and the flat straight lines on both sides are called edges.

4. Exercise: Determine which corners are.

Students, I brought some numbers from the kingdom of mathematics. Please decide which shapes are corners. Which ones are not horns?

After the students reported, the teacher asked why those were not horns. Tell me why.

(d) Use the perspective of activity to explore what the perspective is related to.

1, observation angle

The teacher shows the activity angle of the teaching aid and lets the students observe how it becomes bigger or smaller bit by bit.

Hands-on operation

Take out the activity corner in your hand and follow the teacher to feel the process of the game getting bigger or smaller.

Say, the bigger the angle, the better the openings on both sides of the angle. What did you find?

Students report after observation: the bigger the openings on both sides of the corner, the bigger the corner; Conversely, the smaller the openings on both sides of the corner, the smaller the corner.

2. Compare the angles with your classmates.

Contrast is problematic: some students have long and short horns on both sides.

How do we know whose horn is big at this time?

Students discuss: the size of the angle is related to the size of the openings on both sides of the angle. We can compare and find that the length of both sides of the angle does not affect the contrast.

The teacher asked: Does the size of the angle have anything to do with the length of the side?

Teacher's summary:

Show and fill in the blanks: What does the angle have to do with it?

The bigger the openings on both sides of the angle, the bigger the angle (); The smaller the openings on both sides of the corner, the smaller the corner (). The size of the angle and the length of the side ().

(5) Draw corners

We know so much about horns. Do you want to draw them?

1, the teacher demonstrates the corner painting.

Teacher: From a point, draw a straight line in one direction and then draw a straight line in the other direction.

2. Courseware display.

3. Students summarize how the teacher draws.

Students try to live from different angles and sizes.

Third, consolidation exercise: find a corner of life.

What beautiful pictures the children draw! Corners are still hidden in our lives, even in the classroom. Can you try to find them and see which objects have horns on their surfaces?

In fact, there are still many interesting problems waiting for you to study and explore in the corner world. If you are interested, continue to study after class!

Blackboard design:

Angle understanding

A corner has a vertex and two straight sides.

Reflections on the Teaching of "Knowing Corner" in Grade Three and Grade Two of Primary School

The second-grade children have been exposed to basic geometric figures, and this class is not taught until the first-grade students have learned plane figures. It can be said that students have certain cognitive experience and life experience. However, children's understanding of diagonal is mostly at the level of "a sharp point", so it is difficult to abstract the image of the middle corner in mathematics. After repeated research on the teaching materials, combined with students' cognitive characteristics, I put the focus of this lesson on helping children establish the correct representation of "angle". The initial perception angle has two levels. The design of this lesson is divided into three parts: micro-lesson learning before class; Perceive the correct representation of angle in class and experience the size of angle in operation; Expand and improve after class (find a corner of the house, touch and talk). With this overall idea, this class has broken through the key and difficult points of teaching, and there are also some feelings after class.

1, looking for angles from life and establishing angles in activities.

Introducing the familiar five-pointed star into teaching. After students explain the basic characteristics of angle, they are allowed to point to the angle, make full use of the blind spots in students' cognitive process, and point to the angle repeatedly in combination with the characteristics of the angle, and finally establish the correct representation of the angle. Looking for and pointing to the angle in the transition to life, giving students a process of abstract knowledge, accurately transforming the geometric image of the angle, reflecting the angle from daily use, full of mathematical atmosphere.

2, hands-on operation, perception of the size of the angle.

After the students establish the initial representation of the angle, it can be changed to let the students realize the angle with their own activity angle. The courseware demonstrates the overlapping of two angles with the same size and different sides by overlapping method, so that students can find that the size of the angle has nothing to do with the sides. Arouse students' thinking and inquiry, what is the size of the bottom angle related to? The activity of "Little Duck with Big Mouth" helps students break through difficulties. Obviously, the size of the angle is related to the size of the corner opening, so it is natural to draw a conclusion. Students grow up in activities.

3. Every class is not perfect. Only when there are shortcomings can I keep reflecting and making progress.

(1) The students have learned how to draw corners in the micro-class, but I spend more time in this part of the class, which leads to the tension in the later inquiry activities.

(2) Students have established the basic representation of angle, but the practice of pointing to angle is less and not solid enough.

(3) The use of activity angles is still limited, and the activity angles of individual students are not standardized enough and need to be rectified in advance.

A lesson preparation, a class, a reflection and a promotion, only in this process, can I constantly enrich my arms and make my teaching road go longer.