# Instructor guide: Closed-cycle Casimir work record

Course: Why empty space is not simple

Suggested time: 40–55 minutes

## Learning target

Learners distinguish a measured Casimir interaction from a demonstrated repeatable net-energy cycle.

## Prepare

- Review work as force through distance.
- Draw a four-stage approach/capture/separate/reset loop.
- State that the model uses ideal parallel plates.

## Facilitation moves

- Ask where the apparatus ends, not only where output occurs.
- Keep interaction evidence separate from device performance.
- Have learners circle every external input.

## Misconception checks

- **Any attractive force is a free energy source.** A repeatable source must restore the full system and still deliver positive net work.
- **A negative cycle denies the Casimir effect.** The interaction can be established while the proposed energy technology fails its separate ledger.

## Accessibility and participation

- Use a physical four-card cycle sequence.
- Read scientific notation aloud in powers of ten.
- Provide a high-contrast input/output ledger that does not depend on color.

## Evidence of learning

- Complete four-stage energy ledger
- Correct reversible-limit statement
- Two valid ideal-model limitations

## Extension

Replace the ideal expression with a declared material correction factor and propagate its uncertainty.

## Evidence boundary

Assess the learner's reasoning only within the declared model and recorded observations. Do not upgrade a simulation result into a claim about an unmodeled physical system.