The research queue on Mereth Labs

Bloom's 2 Sigma Problem

Sat, 10 Jan 2026 00:00:00 +0530

In 1984, Benjamin Bloom reported a result that should have reorganised education and mostly didn’t. Students tutored one-to-one under mastery learning performed two standard deviations better than students in an ordinary classroom: the median tutored student outperformed 98% of the control group.

The Forgetting Curve

Mon, 12 Jan 2026 00:00:00 +0530

Memory decays. Ebbinghaus measured the shape of it more than a century ago: the probability of recall falls off roughly exponentially with time since the last review.

R(t) = e^{-t / S}

where $R$ is retrievability, $t$ is elapsed time, and $S$ is the current memory stability. Decay is biology. The schedule of reviews is not.

The Proxy Trap

Wed, 14 Jan 2026 00:00:00 +0530

When a measure becomes a target, it ceases to be a good measure.

The test score is a proxy for learning. Once the system rewards that proxy, with promotion, funding and status all keyed to it, every agent inside rationally optimises the proxy instead of the thing it stands for. Students cram and forget, teachers teach to the test, and the metric inflates while the competence under it stays put.

The Factory Model

Fri, 16 Jan 2026 00:00:00 +0530

The age-graded classroom is a batch process. Students enter in cohorts sorted by manufacturing date (birth year) and advance on a fixed clock, whether or not the current unit is mastered. It is the architecture of a factory line, inherited wholesale from industrial-era logistics.

The Latency Problem

Sun, 18 Jan 2026 00:00:00 +0530

A student does maths homework on Tuesday, turns it in on Wednesday, and gets it back graded on Friday. By the time the correction arrives the brain has moved on and the error has set. The loop is simply too long for the brain to learn from.

The Signalling Problem

Tue, 20 Jan 2026 00:00:00 +0530

The labour market needs to sort people by what they can do. With no cheap, trustworthy signal of competence to go on, it falls back on the degree: a four-year, five-figure proxy that bundles thousands of unrelated skills into one credential and certifies none of them precisely.