As an excellent teacher, it is often necessary to write a speech, which is helpful to improve teachers' language expression ability. How to write the speech? The following is the draft of Primary School Mathematics "Preliminary Understanding of Right Angles" that I compiled for you. Welcome to share.

A Preliminary Understanding of Right Angles 1 I said that the content of this lesson is a Preliminary Understanding of Right Angles. This part of the textbook is about a preliminary understanding of the angle. First, let the students observe the real thing, such as a triangle, a red scarf and a fan, to understand the angle, and then let the students observe the rotation of the hour hand and the minute hand on the clock face to form different angles, and gradually abstract the angle from the real thing. There is no angle defined here, only the shape of the angle, the edges and vertices of the angle are known, and the angle is drawn from a given point. The initial understanding of right angle is based on the initial understanding of time angle in this first lesson.

The specific teaching content of this lesson is the content on page114 ~15 of the textbook and the corresponding "doing and painting", questions 5 ~ 9 of exercise 22 on page 1 16 ~ 65438. The first content of the textbook is to explain what a right angle is with the help of a triangle that students are familiar with. Then ask students to observe the corners on textbooks, envelopes and blackboards to strengthen their understanding of right angles. Then explain that to know whether an angle is a right angle, you can compare it with the right angle of a triangle. Finally, let the students learn to draw right angles with triangles. In the course of "Drawing", some exercises are arranged in the textbook, such as changing the position to judge the figure, folding the right angle with paper, drawing the right angle on grid paper, etc., to help students master the characteristics of the right angle and initially cultivate their hands-on operation ability. Exercise 22, question 5 is the imitation exercise of "painting" 1, exercise 22, question 7 is the imitation exercise of "painting" 3, exercise 22, question 6 is drawing right angles, exercise 22, question 8 is asking students to find right angles, exercise 22, and question 9 is asking students to point out various angles.

Teaching objectives

1, through activities such as watching, watching, comparing, drawing, folding and folding, let students know right angles preliminarily; Ask the students to judge and draw a right angle with the right angle on the triangle.

2. Cultivate students' observation ability and hands-on operation ability through activities such as watching, watching, comparing, drawing and folding.

3. Through discussion, exchange and evaluation, let students learn to cooperate with others, and communicate with others the process and results of thinking, so that students can initially form the consciousness of evaluation and reflection.

4. Make students know the close relationship between mathematics and human life, experience mathematical activities full of exploration and creation, and stimulate students' interest in learning.

Emphasis and difficulty in teaching

Teaching emphasis: make students know right angles, judge right angles on a triangle and draw right angles with right angles.

Teaching difficulty: let students judge and draw right angles with right angles on triangles.

teaching process

Through the understanding and analysis of the teaching materials, I intend to teach according to the following steps.

The first part is the introduction summary:

First, let the students judge which corners are and which are not in some figures, and explain the reasons. Secondly, let the students give examples to illustrate which objects have seen corners. Third, let the students point out which angles are on two different triangles. This part of teaching paves the way for understanding the right angle of this lesson by reviewing the known angles in the last lesson.

The second part is to explore knowledge:

First of all, ask about the angle on the triangle just pointed out: "What do you find when you look at the angles on these two different triangles?" Guide the students to find that there is a same angle on two different triangles. The teacher asked, "Do you know what such a horn is called?" Then explain what a right angle is, abstract the figure of right angle, and explain the mark representing right angle. Then ask the students to illustrate the right angles they see on some objects. By guiding students to observe, compare and give examples, teachers help students to discover and master new knowledge in independent inquiry activities, which is conducive to cultivating students' observation ability, developing students' practical ability, stimulating students' interest in learning, and enabling students to understand the close relationship between mathematics and human life.

Secondly, first show the picture of the first question "Do and draw", so that students can judge which are right angles and which are not. Some of these angles are close to right angles, but they are not right angles, which is controversial. Then let the students discuss in groups. Is there any way to judge whether an angle is a right angle? Then exchange and study in large groups, and the teacher will make appropriate supplements and explanations. Then ask the students to judge by the right angle on the triangle. This kind of teaching allows students to ask questions in contradictions, then think, discuss and explore, find a solution to the problem, and then use the found method to solve the problem, and at the same time verify the scientific and reliability of the found method. In this way, students have a strong curiosity and thirst for knowledge about new knowledge, so that students can actively participate in mathematics learning activities, which is conducive to students experiencing mathematics activities full of exploration and creation and stimulating students' interest in learning.

Third, let the students try to draw a right angle by themselves, and then introduce their own methods. Teachers organize students to study and discuss, give affirmation and guidance. Then, while demonstrating, the teacher summed up the method of drawing right angles with triangles, and asked the students to draw two right angles on square paper with triangles, which is the third question "Drawing". The teaching here fully embodies students' subjective initiative, allows students to experience the diversity of problem-solving strategies and develops the flexibility of students' thinking.

The third part is practical application.

First, finish the second question "Drawing". Let the students take out a piece of paper, fold it at right angles, and then exchange their own folding methods. Cultivate students' practical ability.

Secondly, complete Exercise 22, Question 5, and further consolidate the method of judging right angles by right angles on triangles.

Third, complete Exercise 22, Question 6. By drawing right-angle markers, we can not only see students' ability to judge right angles, but also pave the way for map recognition in the future.

Then, complete questions 8 and 9 of Exercise 22, and develop students' comprehensive application ability by finding right angles and hidden angles.

Finally, summarize the whole class and assign homework to complete the seventh question.

Through the above three steps of teaching activities, the teaching objectives of this course are basically reflected, and the teaching content of this course is completed, so that students can actively observe, try, verify, discuss and communicate in mathematics.

In the activity, the teaching task is successfully completed in the process of watching, watching, comparing, drawing, folding, thinking, speaking and practicing, which embodies the "experience" of mathematics learning and enables students to gain an understanding of mathematics knowledge.

At the same time, we can also make progress and development in thinking ability, emotional attitude and so on.

A preliminary understanding of right angles: a preliminary understanding of right angles.

Teaching purpose:

1. Let the students know the right angle.

2. I can judge right angles and draw right angles with triangles.

Teaching emphasis; Can identify and distinguish right angles, can draw right angles.

Teaching difficulty: judging right angle

Preparation of teaching AIDS and learning tools: The teacher prepares a piece of paper with acute angle, right angle and obtuse angle for each student. Students prepare handkerchiefs, textbooks, cartons, exercise books and paper.

Teaching process:

First, review.

The teacher drew acute angle, right angle and obtuse angle on the blackboard, and said, "We all know the angles, and the sizes of the angles are different, so the sizes of the three angles I drew are different." After drawing, ask the students to point out the vertices and edges of the three corners respectively, and the teacher will write them down.

The teacher pointed to the right angle and said, "Look, is this angle different from the other two angles?" ? This is what we are going to learn today. "

Second, the new lesson

1. Preliminary understanding of right-angle teaching.

The teacher asked the students to find out how many corners there are on the covers of handkerchiefs, textbooks and exercise books. And compare it with the right angle on the blackboard.

Let the students find that the corners on the covers of handkerchiefs, textbooks and exercise books are similar in shape and size to those pointed out by the teacher on the blackboard.

The teacher said, "The corners found on the covers of handkerchiefs, textbooks and exercise books are the same as those on the blackboard. Such an angle is called a right angle. We can use a symbol to express it. " The teacher drew the symbol of the right angle on the right angle.

The teacher asked the students to take a look at the triangle and point out which angle is the right angle. Then, let the students take out the paper and imitate the methods in the book.

Fold at right angles.

The teacher gave the students a piece of paper with three angles, and asked them to use the right angle on the triangle to judge which angle drawn on the paper is the right angle. The teacher said, "first put the vertices together, then put one side of the triangle and one side of the corner together, and then see if the other side is together." Let the students operate by themselves, the teacher patrol and correct the mistakes in time. Then, guide the students to say: if the other side and one side of the triangle are also together, this angle is a right angle; If it doesn't match, the angle is not a right angle. Finally, ask the students to check whether the corner they folded is right angle with the corner on the textbook cover.

2. Do the topic on page 42 of the textbook.

Question 4: Ask students to use the right angle on the triangle independently to check whether the angle in the question is a right angle. Then let the students answer.

3. Teach to draw right angles.

Teacher: "We have learned how to draw corners. So, how to draw a right angle? " While drawing, the teacher said, "Draw an edge first, and combine the vertex of the right angle on the triangle with the left end of this edge, so that one edge on the triangle is also combined with this edge;" Then start from the vertex and draw the other side of the corner along the other side of the triangle, so that you can draw a right angle. "Then, let the students draw a right angle on the square paper with a triangle and say how to draw it again.

Third, consolidate the practice.

1, do the question 1, let the students list all the right angles in what they know, and let some students judge whether it is correct or not.

2. Question 2: Draw a right angle on a square paper. Ask the students to test the triangle with right angles.

Question 5 on page 3.42 allows students who have spare capacity to do it on the nail board. If there is no nail board, you can also draw the added line segment on the book with a ruler or triangle.

4. Question 7 on page 42, let the spare students find the right angle on the paper box they brought, and see who can find it quickly and completely. There are 24 right angles on the boxes of cubes and cuboids. This problem can also be used as a math game to let students compete in groups.

Four. abstract

Teacher: The right angle we study is a special angle. It is very useful in our daily life and plays an important role in geometry knowledge.

Blackboard design:

Right angle. Preliminary understanding

The initial understanding of right-angle teaching plans comes from the excellent recommendation of Mathematics Network. For more resources, please find them on other channels of this website.

The initial understanding of right-angle teaching plans comes from the excellent recommendation of Mathematics Network. For more resources, please find them on other channels of this website.

A preliminary understanding of right angle-the teaching goal of the third draft of primary school mathematics lecture;

1. Combined with life situation and operation activities, I have a preliminary understanding of right angles, and I can judge and draw right angles with a triangular ruler.

2. Enrich students' intuitive understanding of right angles through the process of folding, drawing and painting, and cultivate students' initial concept of space.

3. Through observation and comparison, hands-on operation and other activities, cultivate students' observation ability, preliminary hands-on operation ability and cooperation consciousness.

4. In colorful activities, get positive emotional experience, experience the close relationship between mathematics and life, and feel the beauty of mathematics.

Target resolution:

The orientation of the teaching goal of this course is based on students' preliminary understanding of rectangle, square, triangle and parallelogram and diagonal. Starting from students' existing experience, let students abstract right angles from objects, feel right angles from life, learn to judge and draw right angles with a triangular ruler from hands-on operation, and strive to let students experience the process of knowledge formation and feel the close connection of mathematical life.

Teaching emphasis: a preliminary understanding of right angles.

Teaching difficulties: learn to judge right angles and draw right angles with a triangular ruler.

Teaching preparation: multimedia courseware, triangular ruler, activity angle, etc.

Teaching process:

First, draw corners freely and introduce new courses.

(a) Students can draw corners freely.

1. Choose different sizes of corners to show to all students.

2. Choose one of the corners and name each part of the corner.

(2) Reveal the topic

These angles drawn by students are large and small, but there is a special angle whose size cannot be changed. Have you guessed what angle it is? Today we are going to know right angles. (blackboard writing topic)

Design intention: In view of the students' preliminary understanding of angles in the last class, the design of the lead-in link in this class allows students to draw angles freely. On the one hand, the knowledge of drawing angles was reviewed, and the names of various parts of angles were consolidated. On the other hand, a special angle, right angle, was introduced, which paved the way for the communication between right angle and angle and the teaching of new courses.

Second, hands-on operation, exploring new knowledge.

(1) Draw a trajectory and initially perceive the right angle.

1. Courseware gives example 3.

2. Look at the picture, find the angle and draw it on the picture.

3. Report and communicate, and abstract the angle from the real thing.

4. Observation and contrast: What do these angles have in common?

The teacher pointed out that the above angles are right angles (the courseware shows right angle symbols). This is a special angle.

(2) Find and feel the right angle in life.

1. Find the right angle in the theme map on page 38 of the textbook.

2. Find a correct angle in our life.

3. Find a right angle on a pair of triangular rulers.

(3) To judge a sentence, learn to judge a right angle with a triangular ruler.

1. At right angles to the active angle. Judging from the right angle on the triangular ruler

2. Use a triangular ruler to determine whether the corner on the cover of the textbook is a right angle. (Title 1 on page 40 of the textbook)

(4) Fold and fold to further understand the right angle.

1. Fold a right angle with an irregular piece of paper.

2. Verify whether it is a right angle with a triangular ruler.

(5) Drawing, learn to draw right angles with a triangular ruler. (Example 4)

1. Practice in groups and try to draw right angles.

2. Teacher-student communication to determine the tools. (triangular ruler)

3. The teacher demonstrated painting and summarized the painting methods.

Design intention: Students can experience the close relationship between mathematics and life through mathematical activities such as "looking after". The design of "finding right angles in a triangular ruler" not only consolidates the understanding of right angles, but also lays the foundation for judging and drawing right angles in the future. Then learn to judge the right angle in the link of "judging a sentence, folding a sentence and drawing a sentence" and draw the angle with a triangular ruler.

Third, consolidate practice and deepen understanding.

(1) Exercise 8 Question 6 on page 44 of the textbook

1. Which of the following angles is a right angle?

2. Students can judge independently, and when they encounter difficulties, they can be prompted to compare with a triangular ruler.

(B) textbook page 40 "Do one thing" the second question

1. Count how many right angles there are in the picture.

2. Students judge independently, emphasize the right angle when communicating and reporting, and draw the right angle sign.

(3) Exercise 8 Question 7 on page 44 of the textbook

1. Students draw right angles on the paper (starting from a given point).

2. Remind students to draw right-angle signs.

(4) Exercise 8 on page 54 of the textbook 14

First count how many right angles there are on the surface of the cube, then count how many right angles there are on the surface of the cube and how many right angles there are on the surface of the cuboid. Finally, guide the students to compare and find the characteristics.

Design intention: Through practice, students can deepen their understanding of right angles and develop their initial concept of space in mathematical activities such as observation, judgment and drawing. The last question is intended to communicate the relationship between plane graphics and three-dimensional graphics, which not only deepens students' understanding of right angles, but also understands the characteristics of corners on the surface of three-dimensional graphics, cultivates students' thinking order and feels the beauty of mathematics.

Fourth, class summary.

(1) What did you gain from this class?

(2) Do you have any questions?

Design intention: By summing up and talking about the harvest, let students enjoy the happiness of learning success, and at the same time let students leave the classroom with questions, and cultivate students' good habit of thinking diligently.

A preliminary understanding of right angle-the teaching content of the fourth draft of primary school mathematics handout;

A preliminary understanding of the right angle on page118-19 and "painting" exercise 26, questions 5-9.

Teaching requirements:

1. Make students know right angles, judge right angles on triangles and draw right angles with right angles.

2. Initially cultivate students' hands-on operation ability.

Teaching tools:

A pair of triangular rulers.

Teaching process:

First, review.

1, judge which of the following pictures are angles and which are not, and why?

Judge and explain the names of each part respectively.

2. Find the angle on the triangular ruler.

Second, new funding.

1, know the right angle.

(1) Description: One of the triangular rulers is a right angle.

(2) Show another triangular ruler and find a right angle.

(3) Find a right angle on your own triangular ruler.

(4) Description: You can also draw a right angle (demonstration board performance), and then mark it with the right angle symbol "┐". "

(5) Find the vertex and edge of the right angle.

2. Give an example of a right angle in life.

3. Judgment of teaching right angle.

(1) teaching judgment method.

(2) Practice the 1 question of "painting".

4. Teach to draw right angles.

(1) Demonstrate drawing a right angle and mark it with a right angle symbol.

Please talk about the steps of drawing right angles.

(2) Students practice the third question of "Drawing while doing", and ask them to mark right-angle symbols after drawing.

Third, consolidate the practice.

1. Finish the second question of "Painting".

The teacher and the students folded the paper together, folded it at right angles and marked it with symbols.

2. Complete Question 5 of Exercise 22.

(1) Students' judgment, marked with symbols.

(2) It is pointed out that as long as it coincides with the right angle of the triangular ruler, it is a right angle.

3. Complete Exercise 22, Question 6.

Q: How many right angles do a rectangle and a square have?

4. Complete Exercise 22, Questions 8 and 9.

Fourth, the summary of the full text.

What did you learn in this class? How to judge whether an angle is a right angle?

Verb (short for verb) homework

Exercise 22, question 7.

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