物理是一门以观察实验为基础的自然科学。演示实验在实验教学中占有极其重要的地位,为此,教师必须努力提高演示的艺术性,不仅要保证演示的成功,还要使演示收到良好的效果,给学生留下深刻的印象。一、采用可信度大的对比演示法对比最易于鉴别,对比演示是直观教学的好方法,然而,教师采用对比演示时,应尽可能使相同条件无可怀疑。对于相同时间的前后两次演示对比,应改为同时一次进行,这样,学生的不必要的猜疑就得到了排除,有利于把学生的注意力集中到所要观察的物理现象上。如初三热学提供的“黑色 Physics is a natural science based on observational experiments. Demonstration experiment occupies an extremely important position in experimental teaching. For this reason, teachers must strive to improve the artistry of the presentation, not only to ensure the success of the demonstration, but also to make the demonstration receive good results, leaving a deep impression on the students. First, the use of contrasting presentation methods with a large degree of confidence is the easiest to identify, and contrast presentation is a good method for intuitive teaching. However, when teachers use comparative presentations, they should make the same conditions as unquestionable as possible. For the same time before and after the two demonstrations contrast, should be carried out at the same time, so that students’ unnecessary suspicions have been ruled out, help to focus the students’ attention on the physical phenomena to be observed. As the first three thermal studies provide "black