Why the Practice That Feels Worse Is Building the Better Skill

Two kids step up to a batting cage. The first faces twenty fastballs in a row and by the tenth swing he’s crushing them - clean contact, big grin. The second faces a jumble: fastball, curveball, changeup, in no order he can predict. He looks awful. He mistimes, fouls balls off, walks away frustrated.

Now jump ahead to a real game. The pitcher on the mound is not going to announce what’s coming. Who hits better? The frustrated kid. That’s roughly what a 1994 study of real batters found. The messy, error-filled practice built the one skill that mattered: reading a pitch you weren’t expecting.

In short: the practice that feels best is often the practice that works worst - and the clumsy, mistake-ridden kind is frequently the one building durable skill. This post is about why, and how to use it.

Why this matters

You have limited hours to practice anything - math, an instrument, a language, a sport. So you naturally reach for the method that feels productive. The problem is that the feeling lies.

Smooth, confident practice sessions produce weak, forgettable learning. Awkward, stumbling sessions often produce the skill that lasts. If you don’t know that, you’ll spend your time optimizing for a good feeling instead of a good result - and quit the better method right when it’s about to pay off.

Two ideas explain the batting-cage mystery: interleaving (mixing up what you practice) and desirable difficulties (the rule that some struggle is good for you). Once you can read the signal, “feels worse, works better” becomes something you trust instead of fear.

Blocking versus interleaving: two ways to practice

Let’s name the two strategies.

Blocking means studying one type of problem over and over before moving on. All your fractions, then all your decimals, then all your percentages. It feels smooth, organized, confident.

Interleaving means shuffling different but related types together in one session. A fraction, then a percentage, then a decimal, then back to a fraction - mixed up. It feels choppy, harder, more error-prone in the moment.

Picture three problem types called A, B, and C:

• Blocked: A A A B B B C C C - all of one, then all of the next. Smooth, feels easy.
• Interleaved: A B C B C A C A B - types shuffled together. Choppy, feels hard.

Here’s the contrast that matters:

	Blocked	Interleaved
How it feels	Smooth, fluent	Effortful, bumpy
Errors while practicing	Few	More
What you actually practice	Executing one method	Choosing which method fits
Short-term performance	Looks great	Looks worse
Long-term retention	Weaker	Stronger

Notice the pattern. Almost everything that makes blocking feel good in the moment is exactly what makes it weaker for the long run.

The “feels worse, works better” paradox

Why would harder practice produce better learning? The answer is a split that psychologists Robert and Elizabeth Bjork made famous: the difference between storage strength and retrieval strength.

Storage strength is how deeply something is wired into your long-term memory. Retrieval strength is how easily you can pull it up right now. They aren’t the same thing, and the gap between them is the whole secret.

When you block, you keep the same method loaded and ready. Retrieval strength shoots up - the answer sits on the tip of your brain - so performance looks fantastic. But because you never have to rebuild the method or decide whether it’s the right one, you add little storage strength. You’re coasting on a signal that fades the moment you leave the room.

When you interleave, every new problem forces your brain to drop the last method and reconstruct the right one from scratch. That reconstruction is effortful, and you’ll make mistakes. But retrieving and rebuilding is precisely what deepens storage strength. The struggle isn’t a side effect - it is the learning.

Back to the batting cage: twenty fastballs groove your swing for one pitch (high retrieval strength). Mixing pitches forces you to read and decide every time - and reading-and-deciding is the skill the real game demands.

This is why researchers call these methods desirable difficulties, a term Robert Bjork coined in 1994. They’re conditions that slow you down and raise your error rate during practice but produce stronger, more durable, more transferable learning. Spacing, self-testing, interleaving, varying your study conditions - they all share one signature feeling: they feel worse while you do them.

The evidence: what the studies actually show

This isn’t a nice theory with nothing behind it. The research is unusually clear.

Rohrer and Taylor (2007) taught college students to compute the volumes of four obscure solids. One group practiced blocked, another practiced the same problems mixed. During practice, the blocked group was more accurate - blocking looked like the winner. But on a surprise test one week later, the mixed group scored 63% versus just 20% for the blocked group. Roughly triple the score, from the exact same problems, arranged differently.

Kornell and Bjork (2008) ran a study with paintings. People studied works by twelve artists, either blocked (all of one artist together) or interleaved (shuffled). Then they saw brand-new paintings and had to name the artist. Interleaving won clearly - mixing artists helped people learn each painter’s style. Here’s the twist: afterward, about 78-80% still believed blocking had helped them more. They experienced the better method and still trusted the worse one.

That gap between what works and what we think works has a name: a metacognitive illusion - a systematic error in judging our own learning. Blocking feels fluent, and we mistake fluency for progress.

The classroom evidence is just as strong. Rohrer and colleagues (2020) ran the gold-standard test: a randomized trial of 787 students across 54 classes and 5 schools over four months. One month later, on an unannounced test, the interleaved group scored 61% versus 38% for the blocked group - a large effect for a real-world school program.

The same paradox shows up in physical skills. Shea and Morgan (1979) had people practice movement patterns in a fixed order or randomly mixed. The random group did worse during practice but better on later retention and transfer - an effect motor-learning researchers call contextual interference. Same story, discovered independently in the world of movement.

Common misconceptions

• “Interleaving always wins.” It doesn’t. A large 2019 meta-analysis of 59 studies found a moderate overall benefit - large for confusable visual categories like paintings (learning to tell Monet from Manet), but small and variable for math. Interleaving is a tool, not a magic wand.
• “Smooth practice means I’m learning well.” Backwards. Smoothness is often the warning sign. If it feels a little hard, you’re probably in the productive zone.
• “Never block.” Wrong. You usually need some blocked practice first, just to learn how each method works at all. Interleaving pays off after you can execute each type, when the real challenge is choosing between them.
• “Interleaving means mixing anything.” Bouncing between history, then calculus, then Spanish isn’t interleaving - it’s just task-switching. The benefit comes from mixing related, confusable things within one subject.
• “A dip in practice scores means it’s not working.” Your accuracy will drop during interleaved practice. That’s the method working, not failing. Judge it by a delayed test days later, not by how the session felt.

Interleaving is really a discrimination tool

Here’s the deepest way to understand when interleaving helps. It works best when the things you’re mixing are confusable - similar enough that you might mistake one for another.

Picture an art gallery. Lock yourself in a room with twenty Monets and your eyes glaze over; every painting blurs into the last. But hang a Monet next to a Manet next to a Renoir, and you suddenly see the differences - the loose brushstrokes here, the flat light there. Your brain learns categories by contrast, and contrast requires putting different things side by side.

That’s all interleaving really is: arranging practice so your brain is forced to compare. It’s why the strongest math results come from mixing problem types that look similar but need different methods - so the student has to decide which approach applies. That decision is the entire point.

Which also tells you where interleaving does little: rote vocabulary lists, dissimilar facts, unrelated topics. If there’s nothing to tell apart, there’s nothing for interleaving to sharpen. Save it for things you keep confusing.

How to use this

1. Mix your problem sets. Once you’ve learned each type once, stop doing all of section A then all of section B. Deal them out shuffled - A, C, B, A, C - so every problem forces the question “which method does this one need?”
2. Build a “mixed deck” review. Take old and new material from the past few weeks and shuffle it into one session. This interleaves and spaces at the same time - two desirable difficulties for the price of one.
3. Run a discrimination drill. Pick two things you keep confusing - two grammar rules, two chemistry reactions, two chord shapes - and practice them alternating, back and forth, instead of one at a time. Feel how the contrast sharpens the difference.
4. Block first, then mix. For anything brand-new, do a short block to learn how the method works. Switch to interleaving the moment your real challenge becomes choosing between methods, not executing one.
5. Judge by the delayed test, not the session. Expect to feel clumsy and score lower while interleaving. Trust a quiz a few days later to tell you the truth about what stuck.

Conclusion

The single thing to hold onto: the feeling of ease is not the feeling of learning. Blocking gives you a smooth session and a shallow memory. Interleaving gives you a bumpy session and a skill that survives the real game - as long as you’re mixing things similar enough to confuse.

So treat a little struggle as a signal you’re in the right place, not a sign to bail. And notice how naturally interleaving pairs with its cousin from the desirable-difficulties family: spacing out your practice over time. If mixing what you study builds discrimination, then spreading when you study builds durability - and the reason harder-to-recall is easier-to-keep is a story worth pulling next.