The science

None of the ideas behind falsewrk are new. They are among the most replicated findings in the psychology of learning, and most of them were first studied more than a century ago. What is new is applying them to engineering judgement rather than to vocabulary or exam facts.

Forgetting is predictable

In the 1880s Hermann Ebbinghaus memorised lists of nonsense syllables and measured how much he could relearn after different delays. Retention fell fast at first and then more slowly — the forgetting curve. Later work has refined the shape, but the pattern holds: without practice, what you learned fades, and it fades fastest just after you learned it.

The useful part is what happens when you practise again. Each successful recall makes the memory more durable, so the next decline is slower. That is why the gaps between reps can grow.

Spacing beats cramming

The spacing effect is the finding that the same amount of practice, spread out over time, produces far better long-term retention than practice massed into one session. A large meta-analysis (Cepeda et al., 2006) found the effect across hundreds of studies; the best gap depends on how long you need to remember for, and it grows as the retention interval grows.

So falsewrk does not let you finish a type in one evening. Doing twenty slab problems tonight feels productive, but it trains what you can do while the method is fresh — not what you will still have in three weeks.

Retrieval is the practice

The testing effect, or retrieval practice: actively producing an answer strengthens memory more than re-reading or re-watching the same material. Roediger and Karpicke (2006) showed students who practised recalling a text remembered far more of it a week later than students who studied it again — even though the re-studiers felt more confident.

Every falsewrk rep is a retrieval. You commit to a number before you see anything, and the reveal arrives only after.

Mixing types helps

Interleaving — mixing different kinds of problem rather than doing all of one kind in a block — makes practice feel harder and works better, especially for learning which method applies (Rohrer & Taylor, 2007). In a block, you already know what kind of problem is next; mixed, you have to recognise it. That recognition is half of engineering judgement.

falsewrk serves each type’s first rep before any type’s second, and goes round the types in turn rather than finishing one before starting the next.

Hard is often good

Robert Bjork’s term desirable difficulties (1994) covers all of the above: spacing, testing and interleaving all make practice feel slower and less fluent than the alternatives, and all produce better learning. The trap is that fluency during practice feels like learning, so people choose the easy version.

This is why falsewrk will sometimes turn you away (“done for today”), and why its most important number — Retained — is measured on reps you have not seen for a week.