周长与面积像一对孪生兄弟,似是而非,似非而是,很容易弄混淆。怎么办?一、摸一摸。从生活中找一些物体,先摸一摸它的周长,再摸一摸它的面积。像下图,摸书的周长就是摸书的四周,也就是说绕书边缘一周,有一种“绕圈”的感觉;摸面积就是摸书的表面,可以从书的四周摸到中心,也可以从中心摸到四周,有一种“抹、擦”的感觉。 Circumference and area like a pair of twin brothers, plausible, paradoxical, it is easy to confuse. How to do? Find some objects from life, first touch its circumference, and then touch it’s area. Like the figure below, touch the circumference of the book is touched around the book, that is around the edge of the book a week, there is a “circle ” feeling; touch area is touching the surface of the book, you can touch the center of the book around , You can also touch around the center, there is a “wipe, rub ” feeling.