Acquiring knowledge involves active and constructive processing of new information. There are many ways to acquire new knowledge; however, learning strategies that actively engage students and promote student interactions lead to the strongest learning in STEM students (NRC, 2012; Freeman et al., 2014).
I think "Actively Engage Students" is the key! The more they can be engaged in solving a problem individually or in a group, the more they can learn. Sometimes even a short question with iClicker can lead to an active learning with a better results than just talking and teaching without involving students.