初三学生接触物理不久,再加上对公式变换和单位换算不熟练,觉得《质量和密度》比较难.有些同学遇到计算就放弃,失去解决问题的信心.其实,这部分内容都有对应的解题技巧,我的感受是选择合适的单位制、巧设未知量、利用图像、利用顺口溜记忆,这些技能无论对于初学者,还是对于中考复习都有所帮助. Third day students contact physics soon, coupled with the formula conversion and unskilled unit conversion, that “quality and density” more difficult.Some students encountered in computing to give up, lose the confidence to solve the problem.In fact, this part has a corresponding Problem solving skills, my feeling is to select the appropriate system of units, skillfully set the unknowns, the use of images, use of jingle memory, these skills both for beginners, or for the exam review are helpful.