Video Length: How Long Should a Course Video Be?

Ever wondered what the maximum length a course video should be? Read what the research suggests below.

As the use of video in both online and on campus education has grown substantially - whether due to democratization of video-making hardware and software, or out of necessity - a common question arises repeatedly: what is the maximum length a course video should be?

The longer answer to this question is what you might expect: it's complicated. The research literature is rife with competing recommendations that - perhaps necessarily - make varying assumptions about what constitutes engagement and pedagogical efficacy. In addition, most of the research surrounding attention span focuses on in-person lecture, making its applicability to asynchronous multimedia tenuous at best (Bradbury 512).

Ultimately, "attention span" may be a red herring when it comes to determining a maximum video length. Attention is usually measured by heart rate or galvanic skin response, both of which don't seem particularly indicative of engagement or learning. Instead, let's look at research that focuses specifically on video engagement as it pertains to video length.

One particular source of confusion may be a 2013 blog post from EdX, the Massive Open and Online Course (MOOC) provider. The short article presented watch data from EdX course videos that indicated that most students stopped watching a video after 6 minutes (Guo 2013). EdX's celebrity and the sheer volume of their data (6.9 million video views) led many to believe, then, that research had definitely demonstrated that instructional videos should be no longer than 6 minutes.

However, Larry Lagerstrom at Stanford astutely pointed out in his own study that this article's conclusion was being misinterpreted through no fault of EdX. He underscored that the data were based on video views within a MOOC - a vastly different context from degree-granting postsecondary courses. According to Lagerstrom, “Some are seeking a serious instructional experience, while others may be interested in the MOOC as a free refresher course on previously studied material, and still others may intend only to sample the covered topics here and there” (Lagerstrom 2015). In other words, the folks watching MOOC videos likely don't have the same level of investment in the course material as an average college student.

With this in mind, Lagerstrom did his own study on two computer science courses at Stanford. These classes had 50-75 minute video lectures that could take the place of attendance at the live lecture if students chose. The detailed watch data from the specialized player used in the study indicated that on average about 90% of students watched the entirety of a video, though usually across multiple viewing sessions. The data also indicated that the median watch time for an individual viewing session was 12-13 minutes, with the mean being 17-20 minutes, leading him to conclude that a good guideline for college instructors making course videos is that they should be ideally less than 12 minutes long, and certainly no longer than 20.

For in-person didactic instruction, the length of time that you're assigned to be in the lecture hall naturally dictates how long your lecture should be. But when you're creating course videos, you're freed from those physical and temporal constraints. Try to rally each video around what you might call a "micro objective" - a skill or piece of knowledge that students must acquire in order to achieve the larger learning objectives of your course.

Independent of any pedagogical benefit to your students, there are also a variety of logistical advantages to creating shorter videos:

• Less production time: As you might imagine, shorter videos are easier to design and deliver.
• Fewer captions: You can revise captions for shorter videos more quickly.
• Fewer interruptions: You're less likely to get interrupted (e.g. by family, noise, etc.) when filming shorter videos. Easier re-shoots: It’s easier to do a re-shoot if there’s a problem with your recording.
• Quicker availability: Shorter videos are available more quickly in Kaltura/Canvas since they take less time to process on the back end.
• Better reusability: The more you isolate individual skills and knowledge into separate videos, the more likely it is that you can re-use your videos in other courses as prerequisites, refreshers, remedial resources, or additional instructional material.

Video should still be used selectively and strategically. Lecturing to the camera with a handful of slides isn't a great use of the moving picture. (Check out our article on effective course videos for some ideas.) If you have existing videos that exceed 20 minutes in length, consider finding natural break points in the video and using the Kaltura video editor to make the cuts. You can then link them together thematically using playlists.

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