When producing an instructional video, one would inevitably come to this question:  how long should a video lecture be?

Why you wouldn’t want a 45-minute video lecture?

It is usually not a good idea to provide a mirror image of a full-length, exact replication of classroom lecture online.  There are several reasons why this is not a good option.  First, it takes too long to upload and download; Second, it is usually rather difficult for learners to navigate for the specific information in the lecture.  Third, digital copies of a lecture would increase class absenteeism for students would watch the lecture video without having to go the classroom.   Last but not least, it is technically risky to take a mirror image of your entire lecture online.  For instance, you broadcast a 45-minute lecture but at the 40 minute your computer crashes.   Crying a little may help, but then what?

What are the determining factors?

Answers to the question of the ideal length involves considerations of student attention span, type of lecture content, file size (that have implication for download speed, etc), ease of navigation, software availability, support resources, storage, bandwidth, network connectivity, and the pedagogy you use in teaching.  These all vary with the individual producing the lecture video and the individuals on the receiving end.

In an article about learning object, Professor Harvey of Athabasca University (Canada’s Open University)  emphasizes the need to relate the size (length) to instructional design considerations, which all boils down to the golden rule of instructional design:  “it all depends.”   In this article, Harvey says that the size of the length is determined by “its reusability weighed against the applicability of the LO [learning object] in the instructional context. “   He said it is also possible to aggregate smaller videos into larger ones though doing so may require additional monetary or human resources(Harvey, 2005).    However, doing it the other way around (cutting down long videos into shorter ones) is harder unless the user is rather sophisticated in video editing technologies.

How to break a lecture down in minutes?

Most people advocate shorter, granular video clips produced around specific topics.   The granular items can come through any of the following channels:

• Competency analysis;
• Task analysis;
• Learning objectives analysis;
• Subject matter analysis;
• Other methods of topical analysis

Is it possible to breakdown a web of concepts, skills, knowledge or attitudes into smaller units?  Sure we can, just as we can break a book into chapters, and chapters into sections, and sections into sub-sections.   In a classroom lecture, it is a flow of words that consist of instructional topics, clarifications, feedback, discussions, improvised jokes and what not, but if you really look hard at it, much of the content can be separated into discreet units without losing the quality of the teaching or learning experience.  It just forces one to reflect on another method for presenting the content.   If it is not possible to separate components of a lecture into smaller units, then we should all forget about PowerPoint, which is a combination of specific slides.

What is the normal length of online video clips?

If we can separate content into smaller units, how long should it be?  According to Cultural Anthropology scholar Professor Wesch of Kansas State University, the average length of YouTube video is 2 minutes 46.17 seconds (Wesch, 2008) (Source) .  It looks like that the norm of online videos are within three minutes.  There are some that advocate one-minute mini-lectures as I have shown in an earlier post. However, the availability of ubiquitous high-speed internet connection on campus may make it possible to have a somewhat longer video, for instance, a 50 minute video can be broken down into several 10 or 15 minute ones.   The sum may end up being larger than the total of these parts if some of the otherwise classroom activities can be moved online in alternative formats.  For instance, some of the discussions can become asynchronous forums while much of the lecturing part becomes video lectures.

When it makes sense to have longer clips?

There are also people who advocate longer video clips.   Certain content, such as a speech, deserve to be broadcasted in full because of the close interconnectedness of topics, which may be hard to separate.   By the way, who would like to see a basketball game video being cut out into many smaller units?   (But then again, there are those game highlights you can purchase for 99 cents.)   According to Will Dick of Wikinomics,  Obama attracts more viewers during the 2008 Campaign because of his longer videos.   As a matter of fact, his videos over 20 minutes attract the greatest number of views.   The reason, according to the author, is because people go to Youtube to see more insights that the 5 minutes of CNN coverage may not provide.    But please note that these may not be “instructional videos”.

This post is getting too long in itself.    So I’d better stop by asking you to think:  What’s your idea of the appropriate size for your lecture?

References:

Harvey, B. (2005). Learning Objects and Instructional Design. International Review of Research in Open & Distance Learning, 6(2), 1-6.