Sage on the Stage or Guide on the Side? In 1993, Alison King wrote a paper contrasting these two approaches to teaching in higher education and concluded that active learning was more effective than passive knowledge absorption via lecture.  

Active learning is a flexible description applied to a wide variety of learning activities involving all students being engaged as active participants in the learning process with the guidance of their instructor. Active learning techniques may be individual  and low effort, such as having students engage in a reflection activity. Active learning can include think-pair-share activities, or range to quarter-long experiential learning projects. Simple activities like journal writing, problem solving, and paired discussions are  appropriate for almost any classes, and easy to start. Other techniques are higher effort and take more time,  like case studies, flipped classroom models, gamification, or structured team-based learning.

Incorporating active learning strategies makes lecture more effective. Student have the opportunity to reflect, discuss, or practice a skill, which can help check their comprehension of material or highlight gaps in their knowledge.