小学自然第五册第１２课《压缩空气》中第一知识要点是指导学生认识空气占据空间并有一定的体积 ,而教材中安排的２个实验却因直观性差很难达到预定的教学目的。于是我便设计了一个便于观察和操作的实验 ,具体步骤如下。１ 材料 :一个大漏斗 ,橡皮塞 ,平底烧瓶玻璃管 ,气球 ,烧 The first primary point of Compulsory Air in Primary School Vol. 12 “Compressed Air” is to guide the students to recognize the space occupied by the air and to have a certain volume. However, the two experiments arranged in the textbooks are difficult to achieve the intended teaching purpose because of their poor visual effects. So I designed a test for easy observation and operation, the specific steps are as follows. 1 material: a large funnel, rubber stopper, flat-bottomed glass tube, balloon, burning