讲好初三物理“对流”这节内容,演示好“水的对流”是关键。而教材中演示水的对流是直接向装有冷水的烧瓶里投放一些高锰酸钾晶粒。教学实践中发现此做法的不足是:一、往瓶中放高锰酸钾晶粒时,高锰酸钾立即溶解,水的颜色骤变且随着晶粒的下降水中形成向下的液流。二紫红色高锰酸钾溶液刚 Say good third-year physical “convection” this section, demonstrating “water convection” is the key. The convection of the demonstration water in the textbook is to directly put some potassium permanganate crystals into the flask containing cold water. The deficiency in this practice found in teaching practice is as follows: 1. When potassium permanganate crystals are placed in the bottle, the potassium permanganate dissolves immediately, the color of the water changes rapidly, and the downward flow of water occurs as the crystals fall. . Two purple red potassium permanganate solution just