# Visible-clue single survivor
Skill: [logic.constraints.elimination](/math/skills/logic/constraints-elimination)
Family: Logic, Constraint, Deduction, and Combinatorics
Visible-clue single survivor grows by changing representation, numeric range, constraint count, distractors, language load, and transfer context while keeping the presentation mobile-legible.
## Variations
- 6. Advanced enrichment: Reason about the general method or a non-routine variant.
- 5. Challenge extension: Combine the skill with a second idea, hidden constraint, or explanation requirement.
- 3. Core task: Solve the target skill independently.
- 1. Foundation recognition: Notice the relevant quantity, shape, relation, or constraint before calculating.
- 2. Guided strategy: Use a visible scaffold, model, or narrowing move to choose a valid next step.
- 4. Transfer form: Apply the same idea when numbers, wording, or representation changes.
## Method
Ask a concrete Visible-clue single survivor question before making school-standard claims.
Use constraint_choice_elimination on the same shared class format, with mobile-legible objects and no story-world skin.
Validate the learner state through constraint_choice_elimination; wrong, correct, hint, and reveal states must remain distinguishable.