This packet is everything a parent or guide needs to assess Unit 06 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 triangulating an epicenter from seismograms and explaining what the waves prove about the deep interior.
By the end of the Earthquakes & Earth’s Interior unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Measure the P–S gap; draw distance circles to locate the epicenter.
The student explains what the shadow zone proves (Page 4).
Trace reading, distance conversion, and epicenter 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 locate the epicenter and explain the interior from the waves. 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 |
|---|---|---|
| Earthquakes & waves | ||
| Elastic-rebound theory | fault-rebound model | Rock stores strain along a fault, then snaps back; the rebound is the quake |
| P-wave | primary / compressional wave | Fastest; push–pull motion; passes through solid and liquid |
| S-wave | secondary / shear wave | Slower; side-to-side motion; cannot pass through liquid |
| Surface wave | Love / Rayleigh wave | Slowest but most destructive; travels along the surface |
| Earth’s interior | ||
| Epicenter | surface point above the focus | Point on the surface above the quake; found by triangulation |
| Triangulation | three-circle location | P–S gap gives distance; three distance circles cross at the epicenter |
| S-wave shadow zone | shear-wave gap | Belt where no S-waves arrive — evidence the outer core is liquid |
| Seismogram | seismograph trace | Record of arrivals; the P–S gap is read straight off it |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Elastic-rebound theory | Thinks earthquakes strike with no buildup or cause. | Describes stress on a fault but not the sudden rebound. | Explains how rock stores elastic strain and releases it in a rebound, generating the earthquake and its aftershocks. |
| Seismic wave types | Treats all earthquake waves as the same. | Names P- and S-waves but confuses their motion or speed. | Distinguishes P-, S-, and surface waves by their motion, speed, and the materials each can pass through. |
| Locating an epicenter | Cannot use arrival times to find a quake. | Reads one seismogram but cannot triangulate. | Triangulates an epicenter from the P–S arrival-time gap at three stations and defends the single point where the circles meet. |
| Earth’s interior from seismic evidence | Describes the layers as guesses with no evidence. | Names the layers but not how waves reveal them. | Uses the S-wave shadow zone and wave refraction to argue for a liquid outer core and a solid inner core. |
| Lab technique (earthquake triangulation) | Cannot measure arrival-time differences off a trace. | Measures the P–S gap but plots the distance circle carelessly. | Reads P- and S-wave arrivals precisely, converts the gap to distance, and triangulates a defensible epicenter. |
| 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 the evidence drives the claim: an S-wave that never arrives means the outer core won’t carry a shear wave. Ask “which arrival told you that, and what does it prove about the core?”
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 | Elastic-rebound theory | NY / Appr / Mast | |
| 2 | Seismic wave types | NY / Appr / Mast | |
| 3 | Locating an epicenter | NY / Appr / Mast | |
| 4 | Earth’s interior from seismic evidence | NY / Appr / Mast | |
| 5 | Lab technique (earthquake triangulation) | 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.