We have an intuitive understanding of the cylinder, and through rolling, piling, touching and other activities, we initially feel that the shape of the cylinder is different from that of a cuboid or a cube. Example 1 Teach the understanding of cylinder first, and then teach the understanding of cone. Students should understand their characteristics as a whole, know all the faces around the cylinder or cone, know the height of the cylinder and cone, and measure the height.

When teaching cylinders, the teacher asked us to start by identifying cylindrical objects. In the picture of 1, some objects are cylindrical, some objects are partially cylindrical, and some objects are not cylindrical. Moreover, among cylindrical objects, some are tall, some are short, some are thick, and some are thin, which provides rich concrete objects for understanding cylinders.

The teacher instructed us to observe and communicate, and at the same time made necessary explanations. We look at the cylinder carefully and find that the upper and lower sides of the cylinder are the same circle, the side of the cylinder is curved, and the upper and lower sides of the cylinder are the same thickness. . In the "exercise", the textbook arranged two cups and barrels with different bottoms, two waist drums with the same bottoms but different thicknesses, and a box with a regular hexagonal bottom. We know that these objects are not cylindrical, thus enhancing the experience of cylindrical features. In the process of students communicating cylinder characteristics, teachers can point out that the upper and lower surfaces of the cylinder are called the bottom surface and the curved surface around the cylinder is called the side surface, so that the geometric figure of the cylinder appears in time, and the bottom surface and side surface of the cylinder are marked on the figure, which is an important step in establishing the concept of the cylinder. At the same time, it is pointed out that the distance between the two bottom surfaces of a cylinder is called the height. Marking the height on the geometric figure of the cylinder not only intuitively expresses the meaning of the height, but also enables students to think of the method of measuring the height of the cylinder.

Examples guide students to transfer the learning method of understanding cylinder to understanding cone, abstract the geometric figure of cone on the basis of observing conical objects, and understand the vertex, bottom and side of cone in the process of communicating cone characteristics. The height of the cone is a difficult point in teaching, because the height of the cone is the length of a line segment inside the cone. The textbook points out that the distance from the apex of the cone to the center of the bottom surface is the height of the cone, and draws the line segment from the apex to the center of the bottom surface with a dotted line on the geometric figure of the cone to help students understand the meaning of the height of the cone.