Level 2 · Secondary physics teaching kit · Grades 10–12
Special relativity without shortcuts
Use the learner record during the live investigation, then use the instructor guide to facilitate comparison, address misconceptions, and assess evidence-bounded reasoning.
Learner lab record
Light-cone interval and causality atlas
Which event pairs can exchange a signal, and which descriptions remain invariant when coordinates change?
Setup
Use the light-cone laboratory. Classify event pairs by comparing spatial separation with light-travel distance, then test boundary cases on the cone.
Predict first
- 1. Predict the class when distance equals light-travel distance.
- 2. Predict whether changing inertial coordinates can change the causal class.
| Variable | Role | Unit |
|---|---|---|
| Time separation | independent | s |
| Spatial separation | independent | light-seconds |
| Interval | calculated | light-second² |
| Causal class | dependent | timelike, lightlike, or spacelike |
Observation columns
Analyze
- 1. Which run lies exactly on the cone?
- 2. What does each interval sign mean?
- 3. Why may observers reorder spacelike events without creating a causal paradox?
- 4. What remains locally true in proposed curved metrics?
Conclusion frame
Events separated by ___ s and ___ light-seconds are ___ because ___; every inertial observer agrees on ___.
Instructor guide · 45–55 minutes
Teach the investigation, not the interface
Learning target: Learners classify event separation from the invariant interval and distinguish coordinates from causal structure.
Prepare
- • Draw axes in ct and x units.
- • Prepare one example of each causal class.
- • State the metric-sign convention used by the lab.
Facilitation moves
- • Ask whether a light signal can connect the events before naming the class.
- • Keep events distinct from objects.
- • Return to invariant statements whenever coordinates appear subjective.
Accessibility and participation
- • Narrate inside, on, and outside the cone without relying on the diagram.
- • Use shape and labels in addition to color.
- • Provide a numeric classification table before graphing.
Evidence of learning
- • Three correct causal classifications
- • A boundary-case calculation
- • A coordinate-versus-invariant explanation
Misconception checks
Relativity means every statement is observer-dependent.
Coordinates vary; intervals, causal class, and meetings are invariant.
A warp proposal lets a craft locally pass through light speed.
Metric proposals alter global geometry while local timelike motion remains inside the local cone.
Extension
Apply a Lorentz transformation to one event pair and verify the interval numerically.