How Long Should an Online Lecture Be?


Lectures are an integral part of teaching any lesson. They are not only part of a college classroom’s curriculum; children are introduced to lectures as early as elementary school (albeit smaller lectures, of course). Recent years have shown a surge in online learning, distance learning, e-learning schools, and more, which has led many teachers to question the length of their online lectures.

So, how long should an online lecture be? An online lecture should be no more than 15 minutes long to remain effective while not losing interest.

In this article, you will learn how long an online lecture should be, why online lectures are typically shorter than in-person lectures, and the factors that help determine the length of your online lectures.

How Long Should an Online Lecture Be?

When you think of a lecture, you most likely picture yourself in a classroom, struggling to take notes while your teacher drones on about a topic for 50 to 60 minutes. In the U.S., most high schools and colleges have lecture-based classes that last anywhere from 50 to 90 minutes. So, if traditional, in-person lectures last this long, why should an online lecture be no longer than 15 minutes?

The answer is quite simple – staring at a computer screen to gather information is much less engaging than being in a classroom. Therefore, attention spans drop off more quickly when you are watching a lecture online.

Various research has shown that online lectures should be short, such as:

  • Studies at MIT determined that the most effective length for videos is under six minutes.
  • A study done at the University of Wisconsin revealed that students preferred videos that were shorter than 15 minutes. Additionally, they often used captioning while watching the videos.
  • Dr. Philip Guo, a professor at the University of Rochester, found that student video engagement peaked at six minutes then dramatically dropped off, supporting the findings at MIT.

(Source: Learning Technologies)

The most significant determining factor of the length of an online lecture video is its purpose. Are you going over what was taught in the lesson as a review, or are you introducing a new concept that needs to be thoroughly covered? Is the video one of a series of videos teaching the same content, or is the video intended to stand alone?

The following chart provides some time estimations for online lecture videos based on the purpose of the video:

Purpose of VideoSuggested Length
Recaps and Reviews2 to 5 minutes
Guides, Tutorials, and Video Series6 to 10 minutes
New Content or Concept Introduction15 to 20 minutes

(Source: LearnDash)

Types of Online Lectures and How Type Affects Length

When it comes time to develop your online lectures, their length can vary based on several factors. Some of these factors include:

  • The age of your students
  • The subject you teach
  • The kind of class your lecture is for

The Age of Your Students

Online learning is not just for older children, college students, and adults anymore. Today, many students are enrolled in online courses throughout elementary, middle, and high school. Recording an online lecture for a second-grade class will be much different than recording one for a class of high school seniors.

Before recording your lecture, keep in mind the attention span of your class as well as any other factors that their ages may bring into play. Consider the following:

  • If you are lecturing elementary children, keep videos short, and use lots of visual aids to keep their attention. You may consider filming a video series to teach concepts at this age level because the videos need to be very short.
  • If you are lecturing high school seniors, keep videos less than 15 minutes long and request that the students complete work after watching the video to make sure they’ve watched the entire video. This could be completing worksheets, writing a summary or response after the video, or posting on an online class dashboard to discuss the lesson with other students.
  • If you are lecturing non-traditional adult college students, take into consideration that many of them have families or jobs that require much of their time. Try to keep your videos around 10 minutes each to make it easier for them to attend all of their lectures each day.

The Subject You Teach

All subjects are not created equal. Some are much more challenging to understand than others. The difficulty of the subject you are lecturing about will affect how long your online lectures are.

For instance, if you are lecturing about history, you can likely make various 5 to 7 minute long lectures covering each part of history in the unit instead of one, single long lecture. However, if you are lecturing about physics, you will likely need to make longer lectures to include all of the necessary information your students must learn.

The level of the subject you are teaching will matter, as well. Creating online lectures for a middle school math class will be very different from creating online lectures for a college Calculus class.

When considering the subject you are lecturing about, a good rule of thumb is to split lessons into smaller videos as often as possible.

The Kind of Class Your Lecture is For

Online lectures can be utilized for a variety of learning opportunities, such as:

  • Flipped courses – Flipped courses are a “backwards” take on traditional learning where students participate in online classwork (lectures, discussions, research, etc.) at home and do classwork that resembles homework, which focuses on engaging in the concept they are learning while being guided by a teacher.
  • Web-based courses – Web-based courses are designed to be done completely online at the student’s pace. The course is entirely laid out with all lectures, assignments, assessments, and anything else needed for the course included as soon as the student starts working in it.
  • Web-enhanced courses – Web-enhanced courses are similar to web-based courses, but the class meets at specific times in-person to discuss what they are learning and have the teacher address any questions. The course is still online and allows students to work at their own pace.
  • MOOCs (Massive Open Online Courses) – MOOCs are courses that are open to everyone through the internet. These courses are designed to be done entirely online, cover a myriad of different subjects (not just academic ones), and were made popular by websites such as Udemy, EdX, and Khan Academy. Unfortunately, these courses do not offer official certifications when completed. Their primary focus is to teach new skills or build on old ones.

(Sources: WeCreateOnlineCourses and Student Competitions)

With the different online learning opportunities having various purposes, it is no surprise that online lectures will have varying lengths for different types. For instance, flipped courses can utilize shorter videos that need to be watched each day because the students will be engaging in content activities the next day in class with their classmates and teacher.

Web-based and web-enhanced courses will utilize both shorter and longer videos because they are covering the entirety of the course’s content within a single course. These most often use longer videos to introduce new content and shorter videos for recaps.

MOOCs are not held to any standards by academia as far as course content goes. However, because these courses are generally taken by older adults trying to learn new skills and are optional courses that do not result in certifications, the courses tend to be made up of numerous short videos to keep the attention of their student base while not burning them out.

In Conclusion

Education has come a long way from the chalkboards and long-winded lectures of the past. With the internet came new ways to learn and teach, resulting in online lectures that are much shorter than the lectures of old. When creating your online lecture, be sure to keep in mind your student’s ages, the subject you teach, and the type of course you teach – and don’t forget to keep it less than 15 minutes long!

Glen Brown

I am a Technical Trainer and Manager with over 20 years experience in IT, Education and Business. I have multiple qualifications on each topic including post graduate qualifications. I have a passion for sharing knowledge and using technology to do this. If you would like to know more about me please see the about page of the website.

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