It can be more concrete and profound to know the familiar image of three-dimensional daily necessities and then return to the plane graphics in the textbook.

Pay attention to the concept of graphics, for example, a quadrilateral with four equal sides and four right angles is a square.

Let me give some examples that students often use:

A piece of white paper is rectangular;

Math class is a cuboid;

Dice is a cube;

Table tennis is spherical;

The cup is a (uncovered) cylinder;

The barrel is a truncated cone.