Magnifier, stick. Teaching process. Let students understand the concept of magnification with a magnifying glass, which is very vivid and easy for students to understand. Teachers need to use standard mathematical terms to point out that the shape of the current picture is the same as the original picture, but the size of the picture has changed.

Promote students to change their language thinking. Find the meaning of enlarging and narrowing by swinging the stick, and break through the teaching goal.