This packet is everything a parent or guide needs to assess Unit 03 at home — learning targets, the answers that count as correct, the mastery rubric, calibration examples, and a clipboard score sheet. No multiple-choice test: the student shows mastery by running a side-by-side comparison and stating honestly what it does and does not establish.
By the end of the Trace Evidence unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Compare questioned and known samples side by side.
The student states class vs. individual out loud (Page 4).
Technique, observations, and honest limits kept distinct.
You are making a decision, not adding up points. For each criterion, decide whether the work is Not yet, Approaching, or Mastered — the column language tells you which. A criterion counts as mastered only when the student can both run the comparison and state its honest limits. A student carries three tokens per term; one token buys a re-do of one criterion on another day, so a single bad afternoon never sinks the unit.
Accept any answer in the synonyms column — they are pre-approved as equivalent. The third column flags the confusions that look close but are not yet, so you can coach precisely.
| Canonical answer | Accepted synonyms | Common confusion / discriminator |
|---|---|---|
| Transfer & comparison | ||
| Trace evidence | transferred trace | Small transfers — hair, fiber, glass, soil — left by contact |
| Locard's exchange principle | every contact leaves a trace | Predicts what transfers, so you know what to look for |
| Comparison microscope | dual-stage microscope | Places questioned and known samples side by side in one view |
| Characteristics & limits | ||
| Class characteristics | group traits | Narrow to a group — consistency with a source, not identity |
| Individual characteristics | unique traits | Point to a single source; rare in trace evidence |
| Refractive index | RI; how light bends | A measurable physical property for comparing glass |
| Cross-section | fiber profile | A fiber's shape in slice — a comparison feature, not an ID |
| Questioned vs. known | unknown vs. reference | Evidence of unknown origin compared to a control sample |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Locard's exchange principle | Cannot state why contact leaves transferable evidence. | States the principle but cannot predict what would transfer at a scene. | Uses Locard's principle to predict likely transfers and guide what trace evidence to collect. |
| Hair comparison & its limits | Treats a hair match as proof of identity. | Compares hair features but overstates what microscopy alone can conclude. | Compares hair by microscopy and states its limit — hair is class evidence, not individualizing without DNA. |
| Fiber comparison | Calls two fibers the same without examining them. | Notes color or type but ignores cross-section or dye. | Compares fibers by type, color, cross-section, and dye, and reports them as consistent, not identical. |
| Glass & soil analysis | Cannot describe a physical property that distinguishes samples. | Measures one property but draws a conclusion it cannot support. | Uses refractive index, density, and layering to compare glass and soil as class evidence. |
| Comparison microscopy & documentation | Uses the microscope without a side-by-side comparison or notes. | Compares samples but documents the work inconsistently. | Runs a controlled side-by-side comparison and documents technique, observations, and limits. |
| Integration (cross-domain) | Treats trace evidence as isolated facts; makes no cross-domain connection. | Names a link from trace evidence to history, reading, or writing but cannot defend why it matters. | Connects trace evidence to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
The split between Approaching and Mastered is class vs. individual: not just noting two samples look alike, but stating whether the comparison shows consistency with a common source or true identity. Ask “does that narrow the field, or name one source and no other?”
Read these before you grade. They show what Mastered and Not yet actually sound like, plus the edge cases where you should coach rather than decide on the spot.
Student: ______________________________________ Date: _______________ Guide: _________________________
| # | Criterion | Decision | Notes |
|---|---|---|---|
| 1 | Locard's exchange principle | NY / Appr / Mast | |
| 2 | Hair comparison & its limits | NY / Appr / Mast | |
| 3 | Fiber comparison | NY / Appr / Mast | |
| 4 | Glass & soil analysis | NY / Appr / Mast | |
| 5 | Comparison microscopy & documentation | NY / Appr / Mast | |
| 6 | Integration (cross-domain) | NY / Appr / Mast |
☐ No ☐ Yes — for criterion: __________ Tokens remaining: ☐ 3 ☐ 2 ☐ 1 ☐ 0
NY = Not yet · Appr = Approaching · Mast = Mastered · Unsure between two levels? Circle the lower one and note what a re-do would need.