# How it works · Spaced Learning Practice

Spacing is when. Retrieval is what the learner does. Cepeda et al.: 839 assessments, 317 experiments, 184 articles — best interstudy interval grows with retention interval. No universal “1, 3, 7, 14, 30” cadence.

## Terms

| Term | Role | Not | Implication |
|---|---|---|---|
| Spaced practice | Schedule across time | Shortening a course | Define retention horizon |
| Spacing effect | Observed advantage | Fixed product cadence | Test in context |
| Retrieval | Recall/apply without answer first | Rereading | Scenarios and demos |
| Feedback | Correct and explain | Score alone | Immediate corrective feedback |
| Interleaving | Mix related types | Random unrelated mix | After foundations |
| Microlearning | Short format | Proof of spacing | Sequence required |

## Retention requirements map

Capability, population, consequence of forgetting, horizon, observable behaviour, acceptable error. Starting hypotheses: 30 / 90 / 12-month tables on the HTML page. Optimal gap study (>1,350 people): ~20–40% of a one-week horizon → ~5–10% of a one-year horizon.

## Delivery phases

Diagnostic → Design → Convert → Integrate → Operate → Evaluate.

## Headless engine

Experience → competency graph → scheduler → LRS → experimentation → governance. 1EdTech LTI and xAPI. Transparent rules before adaptive AI. Human SME gates (NIST, UNESCO). Consumer language-learning scheduling research: 12.9M traces, >45% error reduction, 12% engagement — method reference only.

[Evidence](/spaced-learning-practice/evidence/) · [Build](/spaced-learning-practice/build/)