The 90/20/8 rule is Bob Pike’s guideline for designing Participant-Centered Training: teach no more than 90 minutes without a break, chunk content into segments of about 20 minutes, and involve participants at least every 8 minutes. Following it keeps learners alert, gives them time to process what they’re learning, and builds in the review that makes learning stick.
Bob Pike, known as the “trainer’s trainer,” pioneered the Instructor-Led, Participant-Centered approach, which he introduced in 1983 as an alternative to lecture-based training. The 90/20/8 rule is one of its foundations. It gives trainers and presenters a simple rhythm for pacing any session:
| Number | What it means | Why it matters |
|---|---|---|
| 90 | No more than 90 minutes without a break | Attention naturally rises and falls in roughly 90-minute cycles |
| 20 | Chunk content into segments of about 20 minutes | Learners need time to process and consolidate new information |
| 8 | Involve participants at least every 8 minutes | Involvement resets attention and turns listeners into participants |
Research on brain-based learning and adult learning supports each part of the rule.
The brain doesn’t hold attention at a steady level. As Brian Dwyer explains in Innovations in Education and Teaching International, brain-based research shows that a learner’s ability to stay focused follows the natural rise and fall of the neurotransmitters that regulate attention. Periods of high attention are followed by periods of low attention, in cycles of roughly 90 minutes.
If a session pushes past that point without a break, learners tune out, no matter how good the content is. A break, a change of activity, or a change of location lets the brain reset.
Within each 90-minute block, adults learn best when content comes in segments of about 20 minutes, each followed by time to process the new information and to reinforce, elaborate on, and summarize it. Tony Buzan reached a similar conclusion in Use Both Sides of Your Brain, finding that a learning period of 20 to 50 minutes produces the best balance between learning and recall.
In practice, a 20-minute segment might be a short lesson, followed by a pair discussion or practice activity, followed by a quick review before moving on.
Bob Pike based the 8-minute guideline on how people are conditioned to pay attention. For decades, television conditioned audiences to listen for a few minutes before a break. Today the competition for attention is even fiercer, with phones, notifications, and open browser tabs pulling at learners constantly. (For more on this, read Attention Isn’t Shrinking. The Competition for It Is.)
Frequent involvement also improves results, not just attention. A widely cited 2014 analysis of 225 studies by Scott Freeman and colleagues found that undergraduate students in traditional lecture-based science, engineering, and math courses were 1.5 times more likely to fail than students in courses with active learning.
Involvement doesn’t have to be a big activity. A question, a quick poll, a chat response, or a 2-minute pair discussion all count.
The 90/20/8 rule works hand in hand with review. In 1885, German psychologist Hermann Ebbinghaus became the first researcher to study forgetting. He found that people forget most of what they learn within days or weeks unless they review it, and that repetition is one of the simplest and most powerful ways to improve retention.
Later research on “distributed practice,” also called the spacing effect, shows that people learn best when they revisit information over time rather than cramming it all at once. As Dwyer notes, each time learners use what they’ve learned, the memory trace in the brain gets stronger. That’s why Participant-Centered Training builds in regular, learner-led review instead of saving it all for the end.
Here’s how a 90-minute session might look:
For a deeper look at building sessions this way, see Key Components of Designing Instructor-Led, Participant-Centered Training.
Yes, and it matters even more online. In virtual sessions, attention slips faster because distractions are a click away and learners can turn off their cameras. Plan to involve participants even more often than every 8 minutes, using polls, chat, annotation, reactions, and breakout rooms. Many virtual sessions also work better in shorter blocks, such as 60 minutes instead of 90.
It stands for 90 minutes, 20 minutes, and 8 minutes: teach no more than 90 minutes without a break, chunk content into segments of about 20 minutes, and involve participants at least every 8 minutes.
Bob Pike, founder of The Bob Pike Group and creator of Creative Training Techniques®, developed the rule as part of his Participant-Centered approach to training.
Yes. Any presentation, from a team update to a keynote, keeps attention better when the audience is involved every few minutes and content is delivered in short segments.
Anything that asks learners to do something instead of just listening: answering a question, voting in a poll, discussing with a partner, writing a note, practicing a skill, or teaching back a key point.
The 20 and 8 still apply. A 30-minute session should still be chunked into short segments with involvement every few minutes.
Microlearning breaks content into short, standalone lessons, often for self-paced learning. The 90/20/8 rule paces a live session so learners stay engaged from start to finish. The two work well together.
Ready to design training that keeps participants engaged? Explore the workshop that fits you best:
Editor’s note: This post was originally published in June 2024 and updated in October 2026 with a new title, practical examples, guidance for virtual training, and an FAQ.
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