This packet is everything a parent or guide needs to assess Unit 02 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 identifying real igneous rocks and reading each one’s cooling history aloud.
By the end of the Igneous Rocks & Volcanism unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Classify igneous rocks with a hand lens by texture and composition.
The student defends the cooling story the crystals record (Page 4).
Texture, composition, and each rock’s volcanic origin 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 identify the rock and defend the cooling story the crystals record. 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 |
|---|---|---|
| Melt & cooling | ||
| Magma | molten rock below ground | Lava is the same melt once it reaches the surface |
| Intrusive (plutonic) | cooled below ground | Slow, deep cooling → coarse crystals (e.g. granite) |
| Extrusive (volcanic) | cooled at the surface | Fast cooling → fine-grained or glassy texture (e.g. basalt) |
| Texture & composition | ||
| Texture | crystal size / grain size | Records the cooling rate — not how old the rock is |
| Vesicular | full of gas holes | Trapped gas bubbles; pumice can float |
| Felsic | high-silica, light-colored | Sticky, gas-rich melt → explosive; e.g. granite, rhyolite |
| Mafic | low-silica, dark, iron-rich | Runny melt → gentle flows; e.g. basalt |
| Bowen’s reaction series | mineral crystallization order | Orders minerals by the temperature at which they crystallize |
| Volcano form | ||
| Shield volcano | broad, gently sloped cone | Built by runny mafic lava; gentle eruptions |
| Composite volcano | stratovolcano | Layered ash and lava; explosive, felsic melt |
| Cinder cone | scoria cone | Small, steep cone of erupted fragments |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Magma, lava & cooling rate | Cannot say where a rock cooled from its appearance. | Names intrusive versus extrusive but not from the evidence in the rock. | Reads crystal size to tell slow, deep cooling from fast, surface cooling and names the setting. |
| Texture & crystal size | Describes a rock as “rough” or “smooth” with no vocabulary. | Labels coarse or glassy textures but cannot link them to cooling. | Uses texture — coarse-grained, fine-grained, glassy, or vesicular — to reconstruct the cooling rate. |
| Composition & Bowen’s reaction series | Cannot order minerals or tell felsic from mafic. | Sorts felsic and mafic by color but ignores mineral content. | Uses Bowen’s reaction series to rank a melt from ultramafic through mafic and intermediate to felsic. |
| Rock ID (granite, basalt, obsidian, pumice) | Confuses common igneous rocks with one another. | Names some rocks but not from texture and composition together. | Identifies granite, basalt, obsidian, and pumice from texture and composition and justifies each call. |
| Volcano type & eruption style | Treats every volcano as the same cone. | Names shield, composite, and cinder-cone forms but not why they differ. | Reads eruption style from a rock’s composition and matches it to shield, composite, or cinder-cone form. |
| Integration (cross-domain) | Treats the science as isolated facts. | Names a link to history, reading, or writing but cannot defend it. | Connects the unit across History · Reading · Writing and defends why it matters. |
The split between Approaching and Mastered is crystals tell the story: not just naming a rock, but using its texture to say how fast the melt cooled and its composition to predict the eruption. Ask “so what do the crystals tell you?”
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 | Magma, lava & cooling rate | NY / Appr / Mast | |
| 2 | Texture & crystal size | NY / Appr / Mast | |
| 3 | Composition & Bowen’s reaction series | NY / Appr / Mast | |
| 4 | Rock ID (granite, basalt, obsidian, pumice) | NY / Appr / Mast | |
| 5 | Volcano type & eruption style | 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.