? Paper Keywords: Sketch Geometry Teaching Purpose Interest Modeling Law Morphological Structure

? Art major courses in technical secondary schools should start with sketch geometry teaching, aiming at enabling students to master the basic laws of modeling and lay a good foundation for sketch learning in the future. All object shapes can be divided into three categories: square, circle and combination. It is not difficult to see that square classes and circular classes are the most basic types. Their representatives are cubes and spheres. After drawing these two basic geometric figures, any other figures can be extrapolated.

Art is also called plastic arts, and sketch is the foundation of plastic arts, while sketch geometry is an important part of sketch teaching and an essential basic course for art majors in secondary vocational schools. The purpose is to let students master the basic laws of modeling and lay a good foundation for future sketch learning. I have the following thoughts in teaching practice.

First of all, interest is the best teacher

Interest is the most active and realistic factor in learning motivation. Without interest in learning, there is no internal motivation, and there is no consciousness of learning. Such art teaching, the cultivation of aesthetic feeling, will become passive water, trees without roots.

The works in art textbooks are just strange pictures to students. We should show them the beauty of teaching materials step by step, and explain them from the aspects of modeling, composition and connotation, so that students can understand the deep-seated beauty contained in them, let aesthetic education penetrate into each student's heart, touch their heartstrings and guide them to think, comprehend and ponder, so as to gradually cultivate students' feelings and interests in beauty and attract their attention.

The level of specialized courses for students entering technical secondary schools is uneven. How to make poor students' painting level catch up quickly in a short time? Sketch teaching is the most effective method, and geometry teaching has become the most powerful teaching means. How can we attract students' interest in geometry teaching? Nature is the best teacher to cultivate emotions. In art teaching, I will take students to nature, cultivate students' sentiment by sketching nature, and let students love life, discover beauty, appreciate beauty and express beauty; Let the students realize that there are three kinds of objects in nature: square, circle and combination. The natural environment is an important factor to trigger students' rich emotional activities, which can arouse their associations and thus stimulate their specific emotions. Different natural environments affect students' different emotional activities.

Second, art courses should attach importance to the teaching of sketch geometry.

My teaching ideas at the entrance stage of secondary school students are: first sketch the geometric shape of gypsum, and then sketch the still life and gypsum surface; As an important course, sketch should be trained as soon as possible.

1 Several Problems in Sketch Geometry Teaching

(1) The purpose is not clear. It is considered that the geometric shape of gypsum is relatively simple and easy for students to draw, and the geometric shape of sketch is regarded as the same as that of ordinary sketch still life, which loses the significance of teaching the geometric shape of sketch.

② No focus. Let the students draw all the geometric figures, regardless of the key points, and spend the same energy on learning.

③ There are too many geometric figures in each group at the beginning of sketch. Students pay too much attention to composition, light and shade, picture effect and so on.

④ There is no reasonable arrangement order when sketching. Some interlocking contents are not arranged in a reasonable order, so it is difficult to get good results.

⑤ The modeling rules are not clear. Each geometric figure has its own modeling law, and mastering it is the main purpose of our study of sketching geometric figures. If the law of modeling is not clear, the teaching purpose will be difficult to achieve.

The emergence of these problems shows that some teachers and students have unclear understanding of sketch geometry teaching.

2 Correct understanding of geometric sketch teaching

Geometric form is the simplest and most basic form summarized from natural form. Once we have mastered its modeling rules, we can draw inferences to describe any other form in nature. French painter Paul Cézanne pointed out: "No matter how complicated the structure is, all the shapes of objects can be summarized into several geometric shapes, namely, the structural forms of spheres, cylinders, cones and cubes." Summarize concrete images into simple geometric shapes, and then use abstract geometric shapes to understand concrete objects, so as to master the basic laws of shape change. The purpose of drawing geometric figures is to cultivate and train beginners in the simplest and most general concepts of shape and shape, and to master the organic relationship between them. It can be said that sketch is the basis of plastic arts, and sketch geometry is the basis of sketch teaching, so it is the most important.

How to make students learn geometric sketch well

(1) Summarize and classify, and define tasks and key points. There are many kinds of geometric shapes, and it will waste a lot of time if you draw them in general. Some students drew a lot of geometric figures, but they still didn't solve the most basic problems, such as basic perspective, the law of light and shade and so on. The reason is that the key points are not grasped. The emphasis is on the classification of geometric shapes. All geometric shapes can be divided into three categories: one is a square with square characteristics (objects composed of various planes), such as cubes, cuboids, prisms, pyramids and so on. One is round, such as sphere, cylinder, cone, etc. There are also combinations of two or more simple geometric shapes, such as a cone and a cylinder. Among them, the cube is the representative of square geometry, because it has all the main characteristics of square geometry, that is, it is a three-dimensional combination of planes with sharp edges and corners, and there is no transition between planes. Among them, the sphere is the representative of circular geometry, because it has all the main characteristics of circular geometry, that is, it is a solid composed of surfaces or main surfaces, with gradual changes in light and shade and natural transition. Therefore, cubes and spheres are the focus of sketch geometry teaching. The modeling rules of these two geometric shapes should be clear, thorough and thorough. Students should also study these two geometric shapes. When sketching, don't be hasty, but emphasize that the more concrete, profound and meticulous the painting, the better. As for combined geometric figures, they are all composed of basic geometric figures, and their basic modeling rules can be found in basic geometric figures, but they are more complicated than basic geometric figures and cannot be studied as the focus of geometric figure sketch teaching.

(2) To determine the order, we should first say cube, followed by sphere, cylinder and cone. As far as realistic painting is concerned, no matter what you draw, you will encounter perspective problems. Taking a cube as an example, it is the easiest to explain the basic law of perspective. Maybe some people think it's okay to draw from a sphere, but I saidno. On the surface, as long as the outline is drawn round and then the light and shade are drawn, the sphere can be drawn well, and there is no perspective involved. In fact, the light and shade of circular objects can be divided into five basic levels: bright tone, gray tone, dividing line between light and shade, dark tone and reflection, referred to as five tones. These five sounds are mostly distributed in a ring on the sphere. Can it be observed and described from different angles without involving the perspective deformation of the circle? Some people may ask, can't we learn perspective directly by taking a sphere or cylinder as an example? Judging from years of teaching experience and a large number of research materials, it is almost impossible to do so, so we should start with cubes and put cube learning in the first place in sketch geometry teaching.

(3) divide and rule, not greedy. I have met some teachers who think geometry is very simple. At first, they put a lot of geometric figures on the students, and the students' homework was easy to produce results with rich pictures. Some of them can also participate in practice exhibitions, so the students are very happy and the teachers are also very happy. However, in the subsequent sketch homework, there are often some primary mistakes, which are difficult to correct and affect the progress. The reason is that students are required to draw too many films at first, and they pay more attention to composition, light and shade, picture effect, etc., ignoring that the real purpose of drawing geometric figures is to master the rules of sketch modeling. My practice is to study step by step according to the order of cube, sphere, cylinder and cone, and make the perspective law and light and shade law of each geometry clear and thorough. Teaching practice has proved that this method is effective and can get twice the result with half the effort.