There is increasing focus on student centred and student activating learning in university teaching as an approach to enhance deeper and more meaningful learning among students (Prince, 2004). Many courses include a mix of lectures and exercise classes, where students get a chance to solve problems during exercises related to theoretical concepts presented in lectures. Although these exercise classes are student activating in nature, large diversity of the students often make it extremely challenging to find a level of questions that does not leave behind the weaker students, while still being relevant for the stronger students in the class.
I have been involved as a teacher in exercises about nutritional epidemiology as a PhD student, about 10 years ago, and again recently as a Post Doc. Several minor changes to the approach have been made in the meantime, but the exercise classes are still not working well and suffer from problems arising from a huge variation in student background, experience and skills.