实验教学是中学化学教学的重要组成部分，实验的演示与讲解则是进行实验教学的两条基本途径。只有将演示与讲解科学地结合起来，把学生在演示过程中获得的感性认识和在讲解过程中获得的理性认识辩证地统一起来，才有可能获得良好的教学效果。演示与讲解的统一通常有先讲解后演 Experimental teaching is an important part of chemistry teaching in middle schools. The demonstration and explanation of experiments are two basic approaches to experimental teaching. Only when the demonstration and explanation are combined scientifically, and the students’ perceptual knowledge obtained during the demonstration is clearly united with the rational knowledge gained during the course of explanation, it is possible to obtain good teaching results. The unity of presentation and explanation is usually explained first.