微焦距与延时摄影技术在中学化学教学中的应用——饱和溶液

Practice of Microfocus and Delayed Photography Technology in Middle School Chemistry Teaching:Saturated Solution

利用杠杆平衡原理巧妙地将固体溶解、结晶过程表征为杠杆的倾斜,溶解的多少表征为倾斜的程度,利用延时摄影技术将几小时的实验浓缩成几十秒,提高了课堂教学效率,同时使用微焦距拍摄,捕捉蔗糖晶体溶解、结晶时的形状变化,为“不再溶解”提供了多重具有说服力的证据,极大丰富了学生的视觉感观。学生基于实验视频中的实验现象,运用对比分析、推理归纳等科学方法,自主建构饱和溶液与不饱和溶液概念,并从溶质质量、溶剂质量、溶液温度等3个维度建构饱和溶液与不饱和溶液相互转变的模型。通过教师的引导,学生运用控制变量思想建构溶解度的概念。

By using the principle of lever balance,the process of solid dissolution and crystallization is cleverly characterized as the tilt of the lever,and the amount of dissolution is characterized as the degree of tilt.The delay photography technology is used to condense several hours of experiments into tens of seconds,improving classroom teaching efficiency.At the same time,micro focus photography is used to capture the shape changes of sucrose crystals during dissolution and crystallization,providing multiple convincing evidence for“no longer dissolving”,greatly enriching students'visual perception.Based on the experimental phenomena in the experimental video,students use scientific methods such as comparative analysis and reasoning to independently construct the concepts of saturated and unsaturated solutions,and construct a model for the mutual transformation between saturated and unsaturated solutions from three dimensions:solute mass,solvent mass,and solution temperature.Under the guidance of the teacher,students use the idea of controlling variables to construct the concept of solubility.