Use these targets, vocabulary, rubrics, examples, and score sheet with the instructor's approved lesson and procedure. This is an assessment companion, not a complete lesson or safety authorization.
Student lessons, data, and worked answers: Unit 04 learning pathway.
The student demonstrates the following:
Five science criteria plus separately reported integration (Page 3).
Separate an unknown, calculate Rf, compare to a known.
The student states presumptive vs. confirmatory (Page 4).
The run, the Rf values, and the honest limit kept distinct.
You are making a decision, not adding up points. For each criterion, decide whether the work is Developing, Proficient, or Mastery — the column language tells you which. A criterion counts as mastered only when the student can both run the separation and state its honest limits. Each student has three tokens per term; each token retries one rubric criterion. Approved accommodations, equipment failures, and approved absences are handled separately and do not consume these tokens.
Accept listed synonyms; use the distinction column to resolve near-matches.
| Canonical answer | Accepted synonyms | Common confusion / discriminator |
|---|---|---|
| Separation | ||
| Chromatography | separation technique | Pulls a mixture apart by how fast components move |
| Mobile / stationary phase | moving vs. fixed phase | The solvent carries components across the fixed medium |
| Rf value | retention factor | Distance moved ÷ solvent distance — a repeatable number, not a color |
| Testing & limits | ||
| Presumptive test | screening test | Narrows possibilities; a positive is not an identification |
| Confirmatory test | identifying test | Establishes identity; needed before you claim what it is |
| Control | known standard; blank | Run alongside so a result can be trusted |
| Questioned vs. known | unknown vs. reference | Evidence of unknown origin compared to a standard |
| Consistent, not identical | consistent with | What a presumptive comparison can honestly report |
The split between Proficient and Mastery is presumptive vs. confirmatory: a second nonspecific result does not establish specificity. Ask for the blank, reference, hidden QC, and the valid calibration range before accepting a concentration or identification claim.
| Criterion | Developing | Proficient | Mastery |
|---|---|---|---|
| Chromatography principles & the Rf value | Cannot explain separation or define the ratio. | Computes a ratio without a valid origin/front. | Explains mobile/stationary phases; computes dimensionless per-run Rf values, repeated-reading spread, and invalid-front cases from supplied diagrams. |
| Ink & dye separation | Identifies ink from appearance alone. | Compares one band or solvent only. | Compares two-band mixtures with references across both supplied solvent conditions; retains compatible and excluded references without asserting unique identity. |
| Presumptive vs. confirmatory testing | Treats a screen as a final identification. | Names confirmation but ignores specificity. | Distinguishes screening from validated confirmation; explains co-migration, interference, and why repeating the same screen is not independent confirmation. |
| Analyzing an unknown systematically | Guesses a concentration or identity. | Uses a calibration without blank correction or range checks. | Fits the supplied standard curve, subtracts the blank, calculates unknown concentration and QC recovery, and rejects extrapolation or human-effect claims. |
| Technique, controls & documentation | Omits controls or original readings. | Records controls without acting on failure. | Retains coded paper measurements, independent readings, blank/reference status, and failed runs; distinguishes arithmetic checks from empirical method validation. |
| Integration (cross-domain) | Makes no supported connection between the source and the science. | Uses the source but needs help connecting evidence, writing, or limitations to the science. | Independently connects History, Reading, and Writing using a cited source, appropriate evidence, a limitation, and a scientific explanation. |
Read these before you grade. They show what Mastery and Developing actually sound like, plus the edge cases where you should coach rather than decide on the spot.
Student: ______________________________________ Date: _______________ Guide: _________________________
| # | Criterion | Decision | Notes |
|---|---|---|---|
| 1 | Chromatography principles & the Rf value | Dev / Prof / Mast | |
| 2 | Ink & dye separation | Dev / Prof / Mast | |
| 3 | Presumptive vs. confirmatory testing | Dev / Prof / Mast | |
| 4 | Analyzing an unknown systematically | Dev / Prof / Mast | |
| 5 | Technique, controls & documentation | Dev / Prof / Mast | |
| 6 | Integration (cross-domain) | Dev / Prof / Mast |
☐ No ☐ Yes — for criterion: __________
Tokens left this term after this session (choose one): ☐ 3 ☐ 2 ☐ 1 ☐ None left
Dev = Developing · Prof = Proficient · Mast = Mastery · Unsure between two levels? Circle the lower one and note what a re-do would need.