As can be known, active learning includes any type of instructional activity that engages students in learning, beyond listening, reading, and memorizing.  As examples, students might talk to a classmate about a challenging question, respond to an in-class prompt in writing, make a prediction about an experiment, or apply knowledge from a reading to a case study.  Active learning commonly includes collaboration between students in pairs or larger groups, but independent activities that involve reflection or writing - like quick-writes, or real-time polling in lectures - are also valuable.

Actually, instructors can employ active learning in classes of any size, although certain activities may be better suited for smaller classes than large lecture halls.  Nonetheless, even large classes - including classes that meet in lecture halls with fixed seats—can incorporate a variety of activities that encourage students to talk with each other, work in small groups on an activity, or respond to a question through in-class writing or polling.  Furthermore, even small classes can increase student engagement beyond what might occur in a full group discussion by varying the instructional approaches and including small group discussions and activities.

It can be seen that any of the larger scale studies on active learning have been conducted in STEM disciplines, although it reasonable to expect that the benefits of active learning extend to any field.  A 2014 meta-analysis of 225 research studies in STEM classes found that students in classes with active learning performed 6% better on exams than students in classes with traditional lecturing, and that students in classes with traditional lecturing were 1.5 times more likely to fail than in classes with active learning. Additionally, active learning has been shown to decrease the achievement gap for underrepresented minorities and first generation college students.

Finally, active learning strategies come in many varieties, most of which can be grafted into existing courses without costly revisions. One of the simplest and most elegant exercises, called Think-pair-share, could easily be written into almost any lecture. In this exercise, students are given a minute to think about - and perhaps respond in writing - to a question on their own.  Students next exchange ideas with a partner and some students share with the entire class.