watch-glass method

例句：

1. 1. The watch-glass method is a useful technique for observing and recording data.
   观察镜法是一种有用的技术，用于观察和记录数据。
2. 2. In the study of physics, the watch-glass method is often used to measure the speed of light.
   在物理学研究中，观察镜法通常用于测量光速。
3. 3. The watch-glass method has been shown to be effective in improving students' understanding of complex concepts.
   观察镜法已被证明能有效提高学生对复杂概念的理解。