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 reaction, predicting the yield, and explaining the gap between theory and the balance.
By the end of the Stoichiometry unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Run a reaction, weigh the product, compare to the prediction.
The student walks the mole map out loud (Page 4).
Calculations, measured mass, and percent yield 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 math and justify it against the bench result. 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 |
|---|---|---|
| Counting matter | ||
| Mole | 6.022×10²³ particles | A counting unit, not a mass; one mole differs in grams per substance |
| Molar mass | grams per mole | From the periodic table; bridges grams ↔ moles |
| Avogadro's number | N₈ | Particles per mole; bridges moles ↔ particles |
| Reaction arithmetic | ||
| Coefficient | balancing number | Adjust coefficients to balance — never subscripts |
| Mole ratio | stoichiometric ratio | Comes from balanced coefficients; set it up right-side-up |
| Limiting reagent | limiting reactant | Runs out first and caps the product; the other is in excess |
| Theoretical yield | predicted yield | From calculation; compare to the measured (actual) yield |
| Percent yield | actual ÷ theoretical × 100 | Loss is normal; explain where product was lost |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| The mole & molar mass | Treats the mole as just a big number with no use. | Converts grams to moles but slips on Avogadro's number or molar mass. | Moves fluently among mass, moles, and particles using molar mass and Avogadro's number. |
| Balancing equations | Changes subscripts to balance or leaves equations unbalanced. | Balances simple equations by trial but struggles with polyatomics. | Balances complex equations by adjusting coefficients only, conserving every atom. |
| Mole-ratio calculations | Ignores coefficients when relating reactants to products. | Uses the ratio but sets it up upside down at times. | Uses balanced coefficients to convert reliably between any two species in a reaction. |
| Limiting reagent & excess | Assumes reactants always run out together. | Identifies the limiter but cannot find leftover excess. | Determines the limiting reagent, the product amount, and the mass of excess remaining. |
| Percent yield (lab) | Reports product mass with no comparison to theory. | Computes theoretical yield but mishandles the actual measurement. | Measures actual yield, calculates percent yield, and explains sources of loss. |
| 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 setup over answer: a right number from an upside-down ratio is luck. Ask the student to label every unit in the conversion; the units should cancel cleanly.
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 | The mole & molar mass | NY / Appr / Mast | |
| 2 | Balancing equations | NY / Appr / Mast | |
| 3 | Mole-ratio calculations | NY / Appr / Mast | |
| 4 | Limiting reagent & excess | NY / Appr / Mast | |
| 5 | Percent yield (lab) | 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.