教材分析本节课要说的密度一节属于第二部分,这一部分包括了后面所有八章的内容,它们形成了经典力学的初步知识.众所周知,经典力学包括了质量、时间、空间三大基石.初二学生从已有的生活经验中基本具备了绝对的时间观念和空间观念.因而第七章第一节开始就进行绝对质量观的教学,第三节的密度是对质量认识的进一步延伸,是对物质世界认识的进一步探索. The analysis of teaching materials This section of the section on density is the second part. This section includes all the following eight chapters. They form the preliminary knowledge of classical mechanics. As we all know, classical mechanics includes the three cornerstones of quality, time and space. The second-year students basically have absolute time concepts and spatial concepts from their existing life experiences. Therefore, the seventh chapter begins with the teaching of the absolute quality concept in the first quarter, and the third section is the further extension of the quality knowledge in the third quarter. Is a further exploration of the understanding of the material world.