使用试管做演示实验,教室后排的学生往往看不清实验现象.在没有电教设备的情况下,应用以下简易方法,对增强演示效果可起到一定作用.一、做法取大烧杯一只,盛清水多半杯,并把试管夹持在铁架台上.试管下部浸没在水中.衬屏为白色或深色硬纸板.让学生透 Using a test tube as a demonstration experiment, students in the back row in the classroom often fail to see the experimental phenomenon. In the absence of audio-visual equipment, the following simple methods can play a role in enhancing the demonstration effect. First, take a large beaker. Sheng Qing more than half a cup of water, and the test tube clamped on the iron platform. Test tube submerged in water. Lining screen is white or dark cardboard. Let students through