自然教材第九册《热空气》介绍了“同体积的热空气比冷空气轻”的实验装置,通过教学实践证明,学生按此装置实验很难做成功,其主要原因在于:1.学生很难调平衡;2.加热时由于热空气具有上升的性质,易拉罐容易左右摆动,给加热带来了很大的困难;3.给易拉罐加热时,易拉罐周围的空气受热带动易拉罐上升,给学生带 Natural textbook ninth volume “hot air” introduced the “same volume of hot air lighter than cold air” experimental device, through teaching practice has proved that students according to this device is difficult to experiment with success, the main reason is: 1. Students are Difficult to balance balance; 2. Heating due to the hot air has the nature of rising, can easily swing left and right can bring great heating difficulties;