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 skills as a ladder — observation first, defending your findings last. But the real prerequisite structure isn't a straight line: it's a directed graph. These skills are strictly cumulative — the lab notebook is where an observation gets recorded, a measurement only matters once it's written down, and reading a graph rests on both careful measurement and a controlled run. A weak skill early doesn't just cost one rung, it cascades into everything downstream that leans on it. This page is the map a guide uses to find the skill 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 Observation & Asking Questions | — (entry point) |
| 02 The Lab Notebook | 01 (you record what you notice) |
| 03 Measurement, Units & Sig Figs | 02 (a measurement only counts once it's written down) |
| 04 Designing a Controlled Experiment | 02 (a fair test is planned and logged before it's run) |
| 05 Data Tables, Graphs & Patterns | 03 (measurement) + 04 (a controlled run produces the data) |
| 06 Uncertainty, Error & Honesty | 03 (measurement) + 05 (you judge error against data you can read) |
| 07 Lab Safety & Technique | 05 (careful technique is practised while collecting real data) |
| 08 Communicating & Defending Findings | 06 (honest error) + 07 (sound technique) |
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 |
|---|---|
| Communicating a conclusion falls apart (Unit 08) | Uncertainty from Unit 06 — you can't defend a number you can't put honest error bars on. |
| Uncertainty estimates make no sense (Unit 06) | Measurement from Unit 03 — you can't judge error without solid units and sig figs. |
| A graph won't reveal the pattern (Unit 05) | The controlled experiment from Unit 04 — messy variables in, messy data out. |
| The controlled experiment gives no clear result (Unit 04) | The lab notebook from Unit 02 — an unrecorded plan can't be run cleanly. |
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 skills lean on an everyday-math habit — reading a scale for a measurement, plotting points for a graph — that a student may not have solid yet. When the upstream skill node looks solid but the student still stalls, check that supporting habit before re-running the skill demonstration.