Rules you can inspect.

Scheduling

FSRS-6 schedules each retrieval capability. Again maps to rating 1 and Got it maps to Good, rating 3. The desired retention default is 90 percent. Review events retain scheduler and parameter versions so the schedule can be replayed.

Why

Two clear grades match the evidence the learner can provide. Nature by Name does not infer Hard or Easy from response time, confidence, or interface behavior.

Session queue

A separate deterministic policy orders due work, bounded introductions, and delayed retries. Account-wide daily limits prevent a new project from silently multiplying workload. Until done fixes the queue at session start.

What can change it

Queue policy changes require measured learning or workload evidence. Internal priority scores never appear as learner-facing explanations.

Media eligibility and selection

Study photographs must retain identity, rights, attribution, format, availability, and source provenance. Visual recognition requires four eligible photographs. Stable selection rules prefer sourced variation when it exists. There is no AI quality score, popularity vote, or editorial approval claim.

What eligibility means

Eligible means usable for the stated task. It does not mean diagnostic, beautiful, typical, or sufficient for field identification.

Occurrence evidence

Project and Explore rankings use imported reporting records. Claims name the source, place, time range, sample size, and freshness when available. “Most reported” is not “most likely to encounter.” Missing evidence is not evidence of absence.

Progress definitions

Introduced, Learning, Maintaining, and Mastered describe one retrieval capability. Mastered is reversible and requires a long next interval plus delayed successes across varied evidence. Observing an organism, opening its page, or completing an introduction does not prove recall.

Privacy, uncertainty, and known limits

Public profiles and projects show identity and chosen learning scopes. Detailed review history, failures, due dates, answers, and personal confusions remain private. Exact personal locations are not published. The product abstains when media or answer matching is uncertain.

Browser voice capture can fill a Study answer, but automatic voice grading, graded lineage learning, and unfamiliar-organism orientation do not ship until their documented evidence gates pass.