《溶解》一课中,理解“溶解”这个概念既是重点也是难点,它需要掌握两方面的内容,其一是物体由颗粒状变成用肉眼看不见的微粒;其次,微粒是均匀地分散在水中。在教学中,有位老师首先让学生观察盐溶解的整个过程,在交流中得出了第一个结论:盐不是消失了,没有了,而是变成了我们用肉眼看不见的小颗粒,原因是虽然它和清水看起来没两样,但实践经验告诉他们,这杯食盐水 In the lesson of “dissolving”, understanding the concept of “dissolving” is both an important and difficult task. It needs to grasp two aspects. One is that an object changes from granular to invisible particles; second, the particles are uniformly dispersed in Water. In teaching, a teacher first let students observe the whole process of salt dissolution, reached the first conclusion in the exchange: the salt is not disappearing, no, but into small particles that we can not see with the naked eye, The reason is that although it looks the same as fresh water, practical experience tells them that this glass of salt water