我們在讲生理卫生“水的清洁”一节的沙滤池洁治法时,照书上图的原理,采用了如下图的安装模型加以演示說明。课前把必須的材料准备好,在課堂边装、边讲边說明边观察,从安装到清水从沙滤瓶出来,前后不到五分钟。由于瓶为玻璃质,同学亲眼看到了安装过程、內部层次,所以,效果良好。有的同学说:照这个办 We talk about physical health “clean water” section sand filter cleaning method, according to the photo on the principle of the book, using the installation model shown in the following figure to illustrate. Prepare the necessary materials before class, pack up in the class, speak and describe while observing, and remove from the sand filter bottle from installation to clean water in less than five minutes. As the bottle is vitreous, the students saw the installation process, the internal level, so the effect is good. Some students said: According to this