Richard Feynman, the Nobel Prize-winning physicist, had a principle that guided how he learned anything: if you cannot explain it simply, you do not understand it yet. He kept a notebook titled "Things I Don't Know," and when he encountered something he could not explain in plain terms, he would go back to the source material until he could. That feedback loop — explain, identify the gap, return to study, explain again — is what we now call the Feynman Technique, and it is one of the most effective learning strategies available for IT certification candidates.
The reason it works is not intuitive. Most candidates believe they understand a concept after reading about it, watching a video, or following a lab walkthrough. That sense of understanding is almost always an illusion. You have recognized the material, not encoded it. The Feynman Technique forces you to discover the difference.
"The first principle is that you must not fool yourself — and you are the easiest person to fool. When you cannot explain something simply, you have identified a gap in your own understanding, not a gap in your explanation." — Richard P. Feynman, Surely You're Joking, Mr. Feynman!, W. W. Norton, 1985
The four steps
The technique has four distinct steps, and each one serves a specific cognitive function.
Step 1: Choose a concept and write it at the top of a blank page.
Pick something discrete — not "networking" but "how OSPF establishes adjacency" or "what happens during the AWS STS AssumeRole call." Broad topics hide gaps because you can always pivot to the parts you do understand. Narrow concepts expose them.
Step 2: Write an explanation as if you are teaching it to someone with no background.
This is not a summary of your notes. Do not copy phrases from your study guide. Write in your own words, using analogies, and pretend the reader has never heard of the concept. Use plain language. If you cannot avoid technical terms, define each one as you introduce it.
For an AWS certification candidate working on IAM policies, this might look like: "When AWS needs to decide whether you can do something, it looks for a policy that either explicitly says yes or explicitly says no. If there is no explicit yes, the answer is no by default. If there is an explicit deny anywhere in the chain, nothing else matters — the answer is always no."
Step 3: Review your explanation and identify every place where you got vague, wrong, or stuck.
Vagueness is the key signal. Phrases like "it basically does something with the packets" or "it handles the authentication somehow" are your gaps. Mark them. These are the concepts you do not actually understand — you have memorized words without meaning.
Go back to your textbook, documentation, or video. Study specifically those gaps, then rewrite that section of your explanation.
Step 4: Simplify and use analogies.
When your explanation no longer has gaps, try to make it shorter. Replace jargon with analogies where possible. A subnet mask is "a ruler that tells a device which part of an address identifies the neighborhood and which part identifies the specific house." Not technically precise, but functionally accurate and memorable.
Why this works for certification exams
Certification exams — particularly associate and professional-level exams from AWS, Microsoft, and Cisco — are designed to test applied understanding, not rote recall. The AWS Solutions Architect Professional exam, for instance, regularly presents scenarios where you know all the services mentioned but must reason through interactions between them. Candidates who have memorized service descriptions fail these questions. Candidates who can explain each service in plain language and reason about its behavior pass them.
A 2011 study by Karpicke and Blunt published in Science found that retrieval practice — the process of actively reconstructing knowledge from memory — produced dramatically better long-term retention than re-reading or concept mapping. The Feynman Technique is a form of retrieval practice: you close your notes and reconstruct the concept from scratch. The reconstruction effort is the learning event, not the reading.
The technique also helps with what cognitive scientists call "fluency illusion" — the mistaken belief that being able to recognize correct information means you can produce it. Reading the explanation of how BGP path selection works and nodding along creates fluency illusion. Writing your own explanation from memory creates actual understanding.
Applying it to specific certification domains
The following table shows high-value Feynman targets by certification — the concepts where surface-level memorization consistently fails on scenario questions, and plain-language explanation produces the functional understanding that scenario questions require.
| Certification | High-value Feynman targets | What the explanation must cover |
|---|---|---|
| CompTIA Security+ | Symmetric vs asymmetric encryption in TLS | Why RSA for key exchange, AES for data; the speed/asymmetry tradeoff |
| Cisco CCNA | Why STP exists and how it prevents loops | Broadcast storms in Layer 2, STP's port-state election logic |
| AWS SAA-C03 | Private subnet to internet via NAT gateway | Route table entries, NAT GW in public subnet, IGW, public IP requirement |
| AWS SAA-C03 | IAM policy evaluation logic | Explicit deny overrides all; no explicit allow = implicit deny; policy types |
| AZ-104 | Hybrid identity sync options | Password hash sync vs pass-through auth vs ADFS; when each applies |
| CKA | Pod scheduling failure diagnosis | Node selectors, taints/tolerations, resource requests vs limits |
CompTIA Security+ — Cryptography
Cryptography is one of the most commonly misunderstood Security+ domains. Candidates memorize that AES is symmetric and RSA is asymmetric without understanding what that means functionally.
Apply the Feynman Technique: "Why does HTTPS use both RSA and AES?" Write the explanation. If you cannot explain that RSA is used to securely exchange a key because it is slow but asymmetric, and then AES is used for the actual data because it is fast but both sides need the same key, you have a gap. That gap will cost you on multi-step scenario questions.
Cisco CCNA — STP
Spanning Tree Protocol is a domain where many candidates have memorized the steps (elect root bridge, find root ports, find designated ports, block the rest) without understanding why. The Feynman question: "Explain to someone who knows nothing about networking why a loop in a switched network is catastrophic and how STP prevents it."
If you cannot explain broadcast storms in plain terms, your STP knowledge is surface-level. Cisco's CCNA exam will test this understanding through scenarios — a network diagram where you must predict which port will be blocked after a topology change.
AWS Solutions Architect — VPC
"Explain how traffic from an EC2 instance in a private subnet reaches the internet." Write it out. The explanation should cover the NAT gateway, the route table in the private subnet pointing to the NAT gateway, the route table in the public subnet pointing to the internet gateway, the IGW itself, and the public IP on the NAT gateway. Every step matters.
Most candidates can list these components. The Feynman test is whether they can explain the flow without looking at a diagram. Questions about missing routes, misconfigured security groups, or inaccessible instances require exactly this kind of mental model.
Building the Feynman habit into daily study
The technique works best when integrated into your daily study session rather than treated as a separate exercise.
A practical approach: at the end of each study block, close your materials and write a one-page explanation of the most complex concept from that session. Do not grade yourself on completeness — grade yourself on honesty. Mark every phrase that is vague or borrowed from memory without meaning.
Keep your Feynman explanations in a dedicated notebook or folder. Over the course of a study campaign, you will accumulate a set of concept explanations that are far more useful than re-reading your notes because each one was produced by retrieval rather than recognition.
One useful variation: record yourself explaining a concept aloud for two to three minutes. Play it back and listen for hedging language — "and then it kind of does," "which I think is related to," "or something like that." Each hedge is a gap. This variation is particularly effective for verbal learners and for candidates who have trouble detecting vagueness in their own writing.
Common mistakes and how to avoid them
Using technical language as a crutch. Writing "the OSPF router sends a Hello packet to the multicast address 224.0.0.5 to discover neighbors" is not a Feynman explanation — it is a copied sentence. The test is whether you can explain what a Hello packet is trying to accomplish, why it goes to a multicast address instead of unicast, and what happens if a neighbor does not respond.
Stopping at partial understanding. Many candidates write a partially correct explanation, identify one gap, fix it, and stop. The technique requires re-reviewing the full explanation for all remaining gaps, not just the one you expected.
Treating it as a one-time exercise. Feynman explanations decay. A concept you could explain clearly in week three of your study schedule may develop gaps again by week seven if you have not revisited it. Spacing out your Feynman reviews — returning to old explanations every two weeks — maintains the understanding.
Integration with other techniques
The Feynman Technique pairs naturally with spaced repetition. When you create a Feynman explanation for a concept, the date and your honest assessment of remaining gaps can be used to schedule a review. You are not reviewing passively — you are reconstructing the explanation again and comparing it to your previous version.
It also pairs well with practice questions. When you miss a practice question, apply the Feynman Technique to the concept behind the correct answer. Write the explanation before reviewing the explanation in the answer key. The gap between your explanation and the answer key explanation is your precise learning target.
See also: Active Recall vs Passive Review: Why Re-Reading Your Notes Fails
References
- Brown, P. C., Roediger, H. L., & McDaniel, M. A. (2014). Make It Stick: The Science of Successful Learning. Belknap Press. ISBN: 978-0674729018.
- Feynman, R. P. (1985). Surely You're Joking, Mr. Feynman! Adventures of a Curious Character. W. W. Norton. ISBN: 978-0393316049.
- Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772-775.
- Oakley, B. (2014). A Mind for Numbers: How to Excel at Math and Science. TarcherPerigee. ISBN: 978-0399165245.
- Carey, B. (2014). How We Learn: The Surprising Truth About When, Where, and Why It Happens. Random House. ISBN: 978-0812993882.
- Dunning, D., Johnson, K., Ehrlinger, J., & Kruger, J. (2003). Why people fail to recognize their own incompetence. Current Directions in Psychological Science, 12(3), 83-87.
- Bjork, R. A. (1994). Memory and metamemory considerations in the training of human beings. In J. Metcalfe & A. Shimamura (Eds.), Metacognition: Knowing About Knowing. MIT Press.
Frequently Asked Questions
What is the Feynman Technique and how does it apply to certification study?
The Feynman Technique involves writing or speaking an explanation of a concept as if teaching it to someone with no background. For IT certification study, this means closing your notes after a study session and reconstructing key concepts in plain language. The gaps in your explanation reveal exactly what you do not yet understand, which is more useful than re-reading material you can already recognize.
How is the Feynman Technique different from just reviewing notes?
Reviewing notes is a recognition task — your brain confirms that the information matches what it has seen before. The Feynman Technique is a retrieval task — your brain must reconstruct the explanation from scratch. Research consistently shows retrieval practice produces stronger long-term retention than recognition-based review. The effort of reconstruction is what encodes the knowledge.
Which certification domains benefit most from the Feynman Technique?
Any domain with interconnected concepts benefits strongly. Cryptography on Security+, routing protocols on CCNA, VPC and IAM on AWS exams, and Azure Active Directory on AZ-104 are all areas where surface-level memorization fails on scenario questions. The Feynman Technique forces the kind of functional understanding those questions require.
How much time should I spend on Feynman explanations each study session?
Ten to fifteen minutes at the end of each study block is sufficient for most candidates. Write one explanation per session covering the most complex concept from that session. Over a six-week study campaign, you will accumulate thirty to forty explanations — a resource far more useful for final review than highlighted notes or bookmarked videos.
Can the Feynman Technique help with practice question performance?
Yes, particularly for questions you get wrong. When you miss a practice question, apply the Feynman Technique to the correct answer before reading the explanation in the answer key. Writing your own explanation first forces retrieval and exposes your specific misconception. Comparing that explanation to the official answer gives you a precise learning target rather than a passive correction.