Teaching plan and teaching reflection on triangle cognition in the second grade of primary school mathematics

# Grade 2 # Introduction Triangle is a closed figure composed of three line segments in the same plane but not on the same straight line, which is applied in both mathematics and architecture. The following is the arrangement of the teaching plan of "triangle understanding" in the second grade of primary school mathematics and the related materials of teaching reflection, hoping to help you.

Teaching plan of "triangle understanding" in mathematics for the second grade of primary school

Teaching objective: 1. Let students experience the process of understanding triangles in activities such as observation, operation and communication.

2. Know the names of each part of the triangle, draw the height of the triangle, and understand that the triangle has stability characteristics.

3. Experience the wide application of triangle stability in life, and feel the close connection between geometry and real life.

Teaching focus:

Understand the characteristics of triangles; Draw the height in a triangle.

Teaching difficulties:

Understand the meaning of the height and bottom of the triangle, and you draw the height in the triangle.

Teaching preparation:

Multimedia courseware, rectangle, square and triangle learning tools, sticks, nail boards, rulers, triangles.

Teaching process:

First, connecting with reality leads to the subject's perception of triangle.

1, dialogue import.

2. Students report and exchange the information they have collected about triangles.

3. The teacher shows pictures of triangles in life.

The conversation led to the topic: "What do you want to know about triangles? (blackboard title: understanding of triangles. )

Second, hands-on operation, exploring new knowledge.

1. Make triangles by hand and summarize the definition of triangles.

(1) Students use the materials provided by the teacher to operate and choose their favorite way to make a triangle. (Material: wooden stick, nail board, ruler, triangle board. )

(2) Students show the triangle made by communication and talk about how they do it.

(3) Observation and thinking: What do these triangles have in common?

(4) Understand the composition of triangle and preliminarily summarize the definition of triangle.

(5) Teachers show relevant figures to arouse students' doubts, and correctly summarize the definition of triangle through students' thinking and discussion.

(6) Judgment exercises.

2. Understand the base and height of a triangle.

(1) Situation creation.

"There is a Baisha Bridge on the beautiful Yongjiang River in Nanning. Seen from the side, the frame of the bridge is a triangle. Engineers want to measure the distance from the top of the bridge to the deck. What do you think? "

(2) The courseware shows the physical map and plan of Baisha Bridge.

(3) Students try to draw the measurement method on the plan.

(4) Students show and report their own measurement methods.

(5) Students read textbooks and teach themselves the base and height of triangles.

(6) Teachers and students learn the drawing method of triangle height together.

(7) Students practice drawing height.

3. Understand the stability of triangles.

(1) Be prepared to let students feel the stability of triangles in real life.

(2) Hands-on learning tools to experience the stability of the triangle.

(3) Using the stability of triangle to solve real life problems.

(4) Students should understand the application of triangle stability in daily life.

(5) Appreciate the application of triangles in life.

Third, summarize the content of this lesson.

1, students talk about the gains of this class.

Teaching plan of "triangle understanding" in mathematics of the second grade in the second primary school

The teaching goal (1) enables students to understand the meaning of triangle and master its characteristics.

(2) It is beneficial to cultivate students' practical ability, observation ability and induction and generalization ability.

Teaching emphases and difficulties

It is not only the focus of teaching, but also the difficulty of learning for students to understand the meaning and characteristics of triangle by themselves through hands-on practice.

teaching process

Review preparation

1, what are the angles below?

What are right angles, acute angles and obtuse angles?

What are the two lines that make up an angle?

The family drew a right angle (with triangle), an acute angle and an obtuse angle in the notebook.

Summary: We have learned line segments and angles. If we replace the two sides of an angle with line segments and connect the two endpoints of the angle, what figure will appear? (triangle)

Today, let's learn and understand triangles. (Title on the blackboard: Understanding of Triangle)

Learn a new course

1, understand the meaning of triangle.

We have learned about triangles. Can you give an example of which objects have triangles? (red scarf, etc. )

(2) What's the difference between learning tools and making triangles by hand?

(3) Thinking and discussing in combination with the review questions:

① How many line segments form a triangle?

(2) What kind of figure is called a triangle?

On the basis of discussion, guide students to generalize that a triangle is surrounded by three line segments, and the figure surrounded by three line segments is called a triangle.

(4) Consolidate the concept.

Look, which are triangles? (projection)

(2) A figure composed of three line segments is called a triangle. Is this sentence correct? Why?

On the basis of students' answers, the teacher stressed that whether a figure is a triangle depends on two aspects: one is to see that there are only three line segments, and the other is to see whether it is a closed figure.

2, master the characteristics of the triangle.

Just now, we found so many triangles, all of which have different shapes. Let's take a closer look. Are there any similarities between these triangles?

Inspire students to make it clear that they are all surrounded by three lines, and they all have three corners and three vertices.

Then guide the students to sum up: every line segment surrounded by a triangle is called the edge of the triangle, and the intersection of every two line segments is called the vertex of the triangle.

3. The teaching of triangle features.

The triangle we have learned will be used in many places in daily life, such as bicycle racks, beam racks and so on. Why use triangles? Let's do an experiment.

The teacher used the wooden frame prepared in advance and asked the students to pull it.

Pull the pentagonal wooden frame first. (deformation)

Then pull the quadrilateral wooden frame. (deformation)

Pull back the tripod. Can't pull, but the triangle remains the same.

Problem: the triangular wooden frame cannot be pulled through. you do not get it , do you? What conclusions can be drawn?

The students began to practice, and the teacher guided the students to make it clear that when the lengths of the three sides of a triangle are fixed, the shape and size of the triangle are also fixed. Therefore, the triangle has stability. This is the characteristic of a triangle.

Can you name some characteristics of triangles in life? The legs of the chair are loose, and a triangular iron frame can be fixed.

(3) Integrated feedback

1, talk about the meaning and characteristics of triangle.

Reflections on the teaching of "triangle understanding" in mathematics in grade two of grade three.

Triangle is a common figure. In plane graphics, triangle is the simplest polygon and the most basic polygon. A polygon can be divided into several triangles. The stability of triangles is widely used in practice. Therefore, mastering this part of teaching can not only deepen students' understanding of the surrounding things and develop students' spatial concept, but also expand students' knowledge and develop students' thinking ability and ability to solve practical problems in hands-on operation, exploration experiment and mathematics application in life. 1, based on students' existing experience, to mobilize students' initiative in learning.

Students have a preliminary understanding of triangles in their daily life and study, and these knowledge and experiences are the basis for their further study. Therefore, in teaching, we should start from students' existing experience, create colorful scenes and hands-on experimental activities closely related to real life, and help students understand mathematical concepts and construct mathematical knowledge.

When teaching the understanding of triangles, I will show some figures first, so that students can judge which triangles are. When judging, middle school students naturally use existing experience (with three sides and three angles) to judge which ones are triangles, and give reasons for those that are not triangles, such as some that are not closed figures. On the basis of this judgment, we can fully understand and remember what is the mathematical concept of triangle.

2. Let students master knowledge in the process of hands-on practice and active exploration.

Triangles are everywhere in life. When teaching, I ask students to find out where you have seen triangles in your life. They found a lot, such as the frame of variable-speed bicycle, basketball stand and so on. Why do these places use triangles? Can you change it into a quadrilateral? Many students think that quadrangles are easy to deform and triangles should be stable. In order to make students feel this feature more intuitively, I asked students to do experiments with such questions. No one has prepared three pencils, but the deskmate wants to pull it to see if the triangle is stable and prove it by experiments. In this hands-on practice, students not only know the result, but also feel why the triangle is stable. What I have learned will be useful, and then I ask the students to help the teacher solve the problem. What if the latch is broken and the door is always blown open by the wind? With the knowledge and experience just now, it is easy for students to think of building a triangle, and some students have to hold the door as a wooden stick themselves. In this hands-on practice, students have mastered knowledge easily and happily.