Learning by Teaching

Being expected to teach a material can lead to better learning. There are studies that actually demonstrate improved learning outcomes when the students are told beforehand that they will be asked to teach the same material they are trying to learn sometime in the near future. Undergraduate students from the University of California, Los Angeles and Washington University in St. Louis have been shown to perform better in recall tests when informed at the beginning of the study that they would teach the material to others. (John F. Nestojko, Dung C. Bui, Nate Kornell, Elizabeth Ligon Bjork. Expecting to teach enhances learning and organization of knowledge in free recall of text passages. Memory & Cognition, 2014;  Volume 42, Issue 7, pp 1038-1048)

How the expectation to teach helps in learning remains an active area in education research. And with technology, the possible ways of incorporating teaching into the classroom have considerably expanded. Chris Berdik at Slate talks about using a robot as a tutee.

Above copied from Slate
Learning with the expectation to teach is indeed a promising proposition. It is a very cheap intervention since it only involves planting an expectation on a student's mind. The student does not really need to teach. There is one problem, however. Colleges that train teachers should be among the best performing schools in any country. Where else can one find the expectation to teach later so relevant and real? Nemko and Kwalwasser were not particularly manufacturing data when they gave teacher colleges a flunking grade. They wrote:
"Too often, these future educators learn to "teach" math, but they don't necessarily learn how to do the math itself."
Therein lies, I suspect, is the key to making learning by teaching work. It requires something from the students at the very beginning. In Intelligent Tutoring Systems, Matsuda and coworkers at the Carnegie Mellon University found that low proficiency students do not improve their performance with learning by teaching. This can be explained in part by the findings made by Nestojko and coworkers:
"Expecting to teach appears to encourage effective learning strategies such as seeking out key points and organizing information into a coherent structure. Our results suggest that students also turn to these types of effective learning strategies when they expect to teach. It is noteworthy, then, that when students instead expect to be tested, they underutilize these strategies, although our results clearly indicate that these strategies must be available to them and, furthermore, would better serve their presumed goal of achieving good test performance than do the strategies they instead adopt for this purpose. Students seem to have a toolbox of effective study strategies that, unless prodded to do so, they do not use."
The above are now supported by a recent study scheduled to be published in the Journal of Educational Psychology.

Learning by teaching already requires something from the student. There is a minimum proficiency necessary. In addition, the student must already have acquired effective learning strategies. The expectation of teaching simply forces the student to use these strategies. Thus, learning by teaching just brings out what a student already has.