Part of the problem often lies in poor study habits. The students have neglected to do the regular studying required to keep up with understanding the classes. However, another common problem is the conception students have of what is required of them. You just have to be able to regurgitate the information on the test. If students see a course as requiring the memorizing and reproduction of a mass of facts, they simply try to record this information in class.
Most instructors claim that it is the latter which best describes what they want students to do.
If so, they need to overcome some entrenched misconceptions. In particular, there needs to be a focus on the relationship between the factual material and what students need to understand. They may need to be convinced that notes taken in class will be useful afterwards mainly to the extent that they summarize or crystallize their understanding of the material under discussion, rather than simply recording undigested terminology and information. Notes made without understanding are rarely useful. The answer will vary from course to course, depending on such things as textbook resources.