在自然常识“二氧化碳”一课的教学中,探究二氧化碳比空气重这部分内容一直是教学中的难点。主要原因是由实验失败或实验效果不明显而造成的。 教学实践中,为了突破这一教学难点,本人从实验方法和实验现象分析方面,进行了一些探索。 教材中,原实验先在玻璃缸中点燃两支不同高低的普通蜡烛。然后,将集气瓶中的二氧 In the course of teaching common sense “carbon dioxide”, it is always a difficult teaching to explore the content of carbon dioxide heavier than air. The main reason is that the experiment failed or the experimental result is not obvious. In teaching practice, in order to break through this teaching difficulty, I have made some explorations in terms of experimental methods and experimental phenomena analysis. In the textbook, the original experiment first ignited two ordinary candles of different levels in the glass jar. Then, set the gas in the bottle of dioxin