1. Through the process of knowing the perimeter from real life and understanding the meaning of perimeter, we can point out and measure the perimeter of the face and simple figures of objects.

2. Through observation, measurement, calculation and other activities, the concept of space is developed while intuitive experience is obtained, and the idea of "turning joy into straightness" is infiltrated.

3. Through the process of finding problems in practice, analyzing problems in operation and solving problems in practice, we can experience mathematics in real life, develop interest in mathematics, cultivate the ability of independent exploration and cooperative learning, and cultivate mathematical thinking and innovative spirit.

Emphasis and difficulty in teaching: If you know the meaning of perimeter, you will measure and calculate perimeter.

Resource development: from girth connection to measuring waist circumference and head circumference with tape measure, it embodies the life value of mathematics.

Teaching media: line, ruler, tape measure, leaves, short articles, courseware.