This is a working draft for Leslie's review. The dependency edges below are a first pass — the diagram and the prerequisite table are the parts to check hardest, since they drive hold-vs-advance decisions.
The course map shows the eight units as a spine — matter first, electricity and magnetism last. But the real prerequisite structure isn't a straight line: it's a directed graph. Physical science builds on itself more than it looks — atoms and elements rest on measuring matter, telling a chemical change from a physical one rests on knowing atoms, and energy pulls from both changes and motion. A weak concept early doesn't just lower one grade, it cascades into everything downstream that needs it. This page is the map a guide uses to find the concept that's actually blocking a stuck student.
An arrow means “must be mastered first.” Units 05, 06, and 08 each pull from two upstream units — those are the cascade points where one soft prerequisite quietly breaks several later units.
Prerequisite gating
A unit unlocks when its prerequisites are mastered — demonstrated, not merely seen. "Covered in class" is not the gate; a cleared rubric is. The difference matters most at the cascade points, where a soft prerequisite quietly breaks two or three later units.
| Unit | Must have mastered first |
|---|---|
| 01 Matter & Its Properties | — (entry point) |
| 02 Atoms, Elements & the Periodic Table | 01 (measuring matter — mass, volume, density — comes first) |
| 03 Chemical & Physical Changes | 02 (you need atoms and elements to tell a chemical change from a physical one) |
| 04 Forces & Motion | 02 (reading a balance and measuring mass ground the force work) |
| 05 Energy & Its Forms | 03 (energy is stored and released in changes) + 04 (moving things carry kinetic energy) |
| 06 Heat & Thermal Energy | 03 (heat drives many changes) + 05 (heat is one form of energy) |
| 07 Waves, Sound & Light | 05 (a wave carries energy from place to place) |
| 08 Electricity & Magnetism | 06 (a current moves energy and warms a wire) + 07 (light is an electromagnetic wave) |
Gap-cascade diagnosis
When a student stalls late, the visible symptom is rarely the real problem — the broken concept is usually upstream. Trace the arrows backward. Common cascades:
| Late symptom | Upstream concept to check first |
|---|---|
| A circuit won't light and the student can't explain the loop (Unit 08) | Energy transfer from Unit 05 — a current carries energy around a complete loop, and warms the wire (Unit 06). |
| Wavelength and frequency get tangled (Unit 07) | Energy from Unit 05 — a wave is energy on the move, not stuff moving with it. |
| Heat and temperature get mixed up (Unit 06) | Energy from Unit 05 — temperature is average energy; heat is energy transferred. |
| Energy on a ramp doesn't add up (Unit 05) | Forces & motion from Unit 04 — kinetic energy comes from motion (speed and mass). |
Using the graph to plan a re-attempt
The graph turns a "not yet" into a targeted re-attempt instead of a whole-unit re-teach. When a student fails a downstream demonstration:
- Trace backward to the upstream node the symptom points to.
- Re-attempt the upstream concept first — close the gap at its source, not where it surfaced.
- Then re-run the downstream demonstration. Often it passes without any re-teaching of the downstream unit at all, because the cascade is resolved.
This is also where the integration guide matters: some physical science concepts lean on an applied-math idea — ratios and simple circuit math, reading a distance–time graph — from another spoke. When the upstream physical science node looks solid but the student still stalls, check the cross-disciplinary dependency before re-teaching the physical science.