This packet is everything a parent or guide needs to assess Unit 08 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 building a working cell and tracing the electrons through it.
By the end of the Electrochemistry unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Assemble a galvanic cell; measure its voltage.
The student traces electrons anode → cathode (Page 4).
Half-reactions, cell diagram, and voltage 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 build the cell and explain the electron path. 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 |
|---|---|---|
| Electron bookkeeping | ||
| Oxidation | loss of electrons | “OIL” — oxidation is loss; oxidation number rises |
| Reduction | gain of electrons | “RIG” — reduction is gain; oxidation number falls |
| Oxidation state | oxidation number | Assigned by rules; tracks where electrons “count” |
| Redox reaction | electron-transfer reaction | Oxidation and reduction always happen together |
| Cells | ||
| Anode | oxidation electrode | Oxidation happens here in both cell types |
| Cathode | reduction electrode | Reduction happens here; electrons arrive here |
| Galvanic cell | voltaic cell / battery | Spontaneous; produces voltage — opposite of electrolytic |
| Electrolytic cell | electrolysis cell | Non-spontaneous; driven by an external supply |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Oxidation states | Cannot assign oxidation numbers. | Assigns states for simple cases but slips on polyatomics. | Assigns oxidation states correctly across compounds and complex ions. |
| Identifying oxidation & reduction | Confuses which species loses and which gains electrons. | Identifies one half but mislabels the other. | Identifies what is oxidized and what is reduced, with the agents for each. |
| Balancing redox equations | Balances atoms but ignores electrons. | Writes half-reactions but cannot combine them. | Balances redox equations using half-reactions and conserved electron transfer. |
| Galvanic & electrolytic cells | Cannot tell the two cell types apart. | Names the cells but reverses electron flow or electrode roles. | Distinguishes the cell types and traces electron flow from anode to cathode correctly. |
| Lab technique (building a cell) | Assembles a cell that does not work. | Builds a cell but cannot account for its voltage. | Builds a working cell and measures or predicts its voltage from the half-reactions. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
The split between Approaching and Mastered is follow the electron: a student who can point to where electrons leave, where they arrive, and why has it. Ask “trace one electron through your cell.”
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 | Oxidation states | NY / Appr / Mast | |
| 2 | Identifying oxidation & reduction | NY / Appr / Mast | |
| 3 | Balancing redox equations | NY / Appr / Mast | |
| 4 | Galvanic & electrolytic cells | NY / Appr / Mast | |
| 5 | Lab technique (building a cell) | 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.