The Center for Research on Learning and Teaching define active learning as
"....a process whereby students engage in activities, such as reading, writing, discussion, or problem solving that promote analysis, synthesis, and evaluation of class content. Cooperative learning, problem-based learning, and the use of case methods and simulations are some approaches that promote active learning."
In the 2009 article "Active Learning: An Introduction," Felder and Brent use a broad and inclusive definition:
"Active learning is anything course-related that all students in a class session are called upon to do other than simply watching, listening and taking notes."