They're actively engaged in the material, actually seeing the phenomena, by making measurements of real world experiments.

学生们能自主地参与到物质中，看见真切的现象，通过对真实世界实验,做出测量。

麻省理工公开课 - 媒体、教育、市场课程节选

> You can see this frankly in the consumer world.

>坦白说，这种现象在物质世界里处处可见。

哈佛公开课 - 计算机科学课程节选

This is not just a U.S. Phenomenon; many countries around the world are experiencing home price booms and the beginnings of what might be a home price bust.

这个现象并非美国独有,世界上其他国家,也正经历房价暴涨,甚至是崩溃

耶鲁公开课 - 金融市场课程节选

When I posit the existence of atoms with certain structures and certain sort of ways of interacting and combining and building up, when I posit atoms, suddenly I can explain all sorts of things about the physical world.

当我假设原子以某种特定结构存在,以一定的方式相互作用,互相结合,集聚,通过假定原子存在,我立即就能够解释,物理世界中各种各样的现象了

耶鲁公开课 - 死亡课程节选