The content of observing objects appeared three times in the 20 1 1 edition of primary school mathematics textbooks.

They are the observation object in Unit 5 (1) in the first volume of Grade Two, the observation object in Unit 2 (2) in the second volume of Grade Four and the observation object in Unit 1 (3) in the second volume of Grade Five.

1. Longitudinal comparison

Looking at the observation objects in the whole primary school stage, the teaching content presents a progressive relationship and is divided into three levels.

The first stage and the second stage identify the shapes of simple objects and simple geometric objects seen from different positions.

The second level, look around, identify the shapes of geometric assemblies observed from different positions, and observe different geometric assemblies from the same position.

The third level, five times, according to the shape diagram seen in one direction, according to the shape diagram seen in three directions to assemble the geometric assembly.

To sum up, the arrangement of teaching materials first helps students to observe the image of three-dimensional graphics intuitively, establish representations in their minds, and imagine according to the intuitive three-dimensional graphics, and then observe the example graphics from different directions to get the graphics. Then, the spatial imagination is carried out through the established geometric intuition, and the example graphics are restored according to the observed shape diagram through reverse reasoning. So ... Under the guidance of the overall goal requirements, it is decomposed layer by layer and arranged spirally.

2. Horizontal comparison

Then compare it with Soviet Education Edition 20 1 1. The observed object appeared twice in the textbook of Jiangsu Education Edition. They are Unit 7 "Observing Objects" in the first volume of Grade Two and Unit 3 "Observing Objects" in the first volume of Grade Four.

Secondly, observing a unified object from different positions may produce different shapes. Identify the shape of a simple object observed from a certain position, and correctly judge the observer's position according to the seen shape.

4. Example 1 Observe common objects from the front, right side and top. Example 2 observes simple geometry from the front, right side and top, and graphically represents the shapes seen. Example 3 Observe a slightly complicated geometry and show the shape you see. The teaching content of the fifth edition of People's Education Press is based on the shape diagram from one direction, assembled geometrically according to the shape diagram from three directions, and directly put into the exercises in class.

Through the in-depth comparison of the two versions of the textbook, it is found that the contents of the observed objects are actually similar, and the Soviet version only deepened the difficulty of the exercises after class in the second period.

Then, based on the big concept and holistic teaching perspective, I try to integrate the contents of the second and third levels of observation objects appropriately.

Analysis of learning situation: students have learned to observe the shapes of physical objects and simple geometric bodies from different angles, and observe the same object in different positions, and the graphics they see may be the same; Observing different objects in the same position may also see the same figure, which students can basically understand. Just before this class, students' understanding was vague and their expression of the phenomenon was not accurate enough. Teachers' active guidance is needed to help students establish a clearer understanding of mathematics.

Finally, the following teaching objectives are determined in this lesson.

Teaching objectives:

1. Through the process of observation, learn the method of observing objects, know the shapes of geometric assemblies observed from different positions, and infer the three-dimensional shapes of objects according to the observed plane figures.

2. By observing objects, let students go through a series of processes such as observation, comparison, reasoning, generalization, imagination and guess. Develop students' thinking ability and broaden their spatial imagination.

3. Through students' mutual deduction of the "space" and "plane" of three-dimensional graphics, students can strengthen their in-depth understanding of the space and plane of objects, infiltrate the changing and unchanging philosophical thoughts, and form a good habit of observing and thinking from multiple angles.

Teaching emphases and difficulties:

Key points: Through observation, correctly identify the plane figure obtained by observing the geometric combination from different directions.

Difficulty: conjecturing splicing objects according to plane figures.

On the Teaching Process

? First, life activates old knowledge.

In the lead-in session, students' existing knowledge and experience are activated through picture appreciation, so that students can feel that the observed results may be different when looking at the same object from different angles.

Second, multi-level hands-on operation.

The first level (1) observes an object from different positions.

1. Swing.

(1) According to the diagram seen in one direction, try to put it together:

(2) according to the two directions of the graphics you see, start to put them together:

(3) according to the three directions to see the graphics, continue to put together:

secondary

(2) Exploration IV? Other geometries include

1. Place geometry

(1) Group cooperation:

(2) Students show:

Draw a picture

summary

The third stage (3) assembles the corresponding geometry according to the plane figure.

An object, when we observe it from different positions, can draw the figure we see. Conversely, according to the figures observed from different positions, can you imagine how this object should be placed?

1. Think about it.

(1) If these two conditions are met, how many pieces can be put at most? Don't pose, just imagine, what is your imaginary object?

(2) How many pieces do you need at least?

(3) Group cooperation:

① Pendulum: Use 9 cubes to pose a geometric figure that meets these two conditions?

② Thinking: How can these nine small cubes be arranged to meet these two conditions?

Students work in groups and show them together.

2. Lenovo (brand name of computer)

exchange; communicate