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如何设计演示实验,使每一位学生都能感受演示实验带来的视觉冲击,通过演示实验使学生具体地认识物质的外表特征、物质变化的条件和现象,顺利地形成概念和确信理论的真实性?一、实物投影让现象一览无遗有些演示实验只需要观察实验现象,教师在教室前面演示时大多数学生不能真正地看清变化过程,若使用实物投影仪将实验呈现出来,实验现象将一览无遗。如在演示金属钠与水的反应时,可以借助实物投影仪来展示,在培养皿中加入少量水,滴几滴酚酞,投入少量金属
How to design a demonstration experiment so that every student can experience the visual impact brought by the demonstration experiment and enable the students to concretely understand the appearance characteristics of the material and the conditions and phenomena of the material changes through demonstration experiments so as to form the concept and the truth of the theory smoothly First, the physical projection make the phenomenon glance Some demonstration experiments only need to observe the experimental phenomenon, the teacher in front of the classroom presentation most of the students can not really see the process of change, if the use of physical projector to experiment, the experimental phenomenon will be an overview Endless. As demonstrated in the reaction of sodium metal and water, you can use the physical projector to display a small amount of water in the Petri dish, a few drops of phenolphthalein, put a small amount of metal