I've spent hours studying, then gone to use it two weeks later and drawn a complete blank.

For a long time I thought that was just how my brain worked. Like maybe I'm just not the kind of person who retains things well.

Turns out it wasn't me. It was the method.

I'm a Senior Applied Scientist at Amazon. I came from a non-tech background and taught myself most of the skills that got me where I am. And I've mentored almost two hundred people into AI and ML roles, so I've watched this play out hundreds of times. They're putting in the hours, doing the courses, and when it actually matters like in an interview, on the job, when someone asks them to explain a concept they studied last month *it's gone*

The problem isn't effort. It's that most of us were never taught how learning actually works. So I'm going to show you the system I use to retain what I study. It's backed by cognitive science, and most of it goes against what feels productive, which is exactly why it works.

The Illusion of Learning

The first thing I changed was how I reviewed material.

I used to re-read. That was my whole strategy. Go through the notes again, go through the documentation again, maybe highlight some stuff. And it felt productive. After a couple passes, the material starts to feel familiar.

But here's the thing — there's a well-documented phenomenon in cognitive science called the fluency illusion. Your brain recognizes familiar material and mistakes that recognition for actual knowledge. You're not learning. You're pattern-matching. You see something you've seen before and your brain goes, "Oh yeah, I've got this."

But recognition and retrieval are completely different cognitive processes. And the one that matters — on the job, in an interview, when you're actually trying to apply something — that's retrieval.

So here's the fix.

After you study something, close everything. Close the docs, close the tutorial, close your notes. And try to remember what you just learned from scratch. Write it down, say it out loud, whatever works. But the point is you're pulling it from memory, not looking at it again. This is called active recall, and it's one of the most impactful changes you can make.

This isn't just my opinion. Research shows that students who test themselves retain roughly 80% of material after a week, compared to about 34% for those who just re-read.

The reason it works is that retrieving information strengthens the neural pathways associated with it. Re-reading strengthens recognition. Retrieval strengthens recall. And those are not the same thing.

I know it feels harder. That's actually the point. The difficulty is what makes it work.

Now here's the part that really surprised me when I dug into the research. You don't even have to know anything yet for this to help.

There's a technique called pre-testing — basically, quizzing yourself on material before you've learned it. You'll get the answers wrong. That's fine. That's the point. A 2025 study in Memory & Cognition confirmed what earlier research suggested: attempting to answer a question before you know the answer primes your brain to encode the correct answer more deeply when you encounter it later.

Think about what that means for how you approach a new course or a new topic. Before you watch the lecture on, say, gradient descent, try to explain to yourself what you think it is. You'll probably be wrong. But when the actual explanation hits, your brain is already primed to absorb it because you've created a gap it wants to fill.

So the system isn't just "test yourself after." It's test yourself before and after. Bookend every learning session with retrieval, even when you don't know anything yet.

But there's another step that's really important to make this work.

The Spacing Problem

Let's say you start doing active recall. You can actually pull the material from memory without looking at your notes. You feel good.

Two weeks later, it's gone.

And this is where a lot of people get frustrated, because they did the work. They studied correctly. They tested themselves. And they still forgot most of it.

Ebbinghaus mapped this out in the 1800s. It's called the forgetting curve, and what it shows is very sad: without review, you lose roughly 80% of new information within 48 hours. It doesn't matter how well you learned it in the moment. One strong study session is not enough.

This is why people finish a course and three months later it's like they never took it. One exposure — even a really good one — doesn't create durable memory.

The fix is spaced repetition, or reviewing at expanding intervals. You review the material one day after learning it. Then three days later. Then a week. Then two weeks. Each time you retrieve, you push the forgetting curve further out. The intervals get longer because the memory gets stronger.

A meta-analysis found that combining spaced repetition with active recall improves outcomes by about 25% more than using either strategy alone. So these first two methods aren't just additive — they compound.

The key thing is that spaced repetition doesn't actually require more time, just different timing. Instead of one four-hour study block, try doing four shorter sessions spread out over two weeks.

Interleaving

Now there's one more trap I want to flag, because it's related to everything we just talked about.

Most people study topics in blocks, like a week or two on a given topic before you move on to the next one.

But the research says this is another fluency illusion. When researchers compared blocked study against interleaved study — where you shuffle topics instead of doing them in neat blocks — the interleaved group scored 63% on a delayed test versus 20% for the blocked group. But weirdly, during practice, the blocked study group felt like they were learning better.

Your subjective sense of "I'm getting this" is lying to you. Again.

Interleaving works because it forces your brain to constantly identify which concept applies and how it differs from the last one. That's the kind of thinking you actually need in an interview or on the job — not "I studied neural networks for three hours straight," but "given this problem, which approach is the right one?"

I'm not saying you need to overhaul your whole study plan around this. But when you're doing those spaced review sessions, mix the topics up.

And while you're at it, there's one more tip I have to make everything stick. This is the one that feels the strangest — but it's the one that consistently produces the best retention for me.

The Walk & Talk Method

I walk around and talk to myself out loud about the topic. Like actually out loud. Like I'm explaining it to someone who isn't there.

I know that sounds ridiculous. But hear me out, because this is the part of my system that I think most people have never tried, and it changes everything.

Most studying is passive and single-channel. You're sitting, reading, and maybe typing. One input mode. But the brain encodes information more deeply when multiple systems are engaged simultaneously. This is called dual coding, and it's backed by a solid body of research on embodied cognition.

Here's why the walk-and-talk works:

When you're walking, your motor cortex is active. Movement creates a different physiological state than sitting, and that state affects how information is encoded.

When you're speaking, you're forcing yourself to organize information into language. And this is where it gets fun and slightly painful, because you can't explain something out loud without actually understanding it. When you try, the gaps become obvious immediately. You'll be going along fine and then suddenly stumble on a part you thought you understood but can't actually articulate. That's the Feynman technique in action — if you can't explain it simply, you don't understand it yet.

And when you hear yourself, you get an auditory feedback loop. Another input channel for the same information.

So you've got movement, speech production, and auditory processing all happening at the same time, and all encoding the same material. Three channels instead of one.

I do this most mornings. Some concepts I've talked through ten or more times. Those are the ones I don't hesitate on in a technical discussion. They're not stored as something I read once. They're stored as something I've explained, heard myself explain, and physically moved through. That's a completely different kind of memory.

Now, if you're thinking "this all makes sense, but I know myself — I'll do it for a week and then fall off" — that's exactly why I built the AI/ML Career Launchpad. It's a learning community for aspiring AI and ML professionals where you've got structure, accountability, and other people going through the same thing. Because the system only works if you actually use it consistently.

So here's what this comes down to. Everything most people do to study — re-reading, highlighting, cramming — feels productive. And that feeling is the trap.

The system that works is uncomfortable by design. That discomfort is the learning.

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If you're feeling like you need some support with your AI/ML career, here are some ways I can help: