一、重点、难点:1.知道质量的概念及其测量方法2.掌握密度的概念、公式和单位3.会查密度表,知道水的密度4.掌握天平的使用方法和密度的测定5.知道密度公式的灵活应用二、知识的梳理:质量:1.定义:物体所含物质的多少叫质量。2.单位:国际单位制:主单位kg,常用单位:t、g、mg对质量的感性认识:一枚大头针约80mg一个苹果约150g一头大 First, the key and difficult: 1. Know the concept of quality and measurement methods 2. Grasp the concept of density, formulas and units 3. Will check the density table, that the density of water 4. Grasp the balance of the use of methods and density determination. Know the flexible application of density formula Second, the knowledge of the carding: Quality: 1. Definition: how many substances contained in the object called quality. 2. Unit: SI system: the main unit kg, commonly used units: t, g, mg perceptual understanding of quality: a pin about 80mg an apple about 150g large