This packet is everything a parent or guide needs to assess Unit 02 at home — the technique targets, the calibration anchors, the mastery rubric, and a clipboard score sheet. No written test: the student shows mastery by opening a real specimen and locating, naming, and explaining its structures while you watch.
By the end of the Earthworm unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Open the specimen and locate, name, and explain real structures — watched live.
The student explains why each structure does its job (Page 4 anchors).
Careful observations of the external and internal structures 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 perform the technique cleanly and locate, name, and explain the structures on the actual specimen. 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 |
|---|---|---|
| External landmarks | ||
| Clitellum | saddle; band | The smooth, swollen band near the front; secretes the cocoon — not a random thickening |
| Segment | metamere; annulus | The body is built of repeated segments; count from the anterior end |
| Setae | bristles; chaetae | Tiny bristles on each segment that grip the soil; felt more than seen |
| Anterior / posterior | front / rear | The mouth end is anterior; the clitellum sits toward the front and orients the worm |
| Digestive tract | ||
| Pharynx | throat | Muscular; pulls food in at the anterior end, ahead of the crop |
| Crop | storage sac | Thin-walled; stores food before the gizzard — softer than the gizzard |
| Gizzard | grinding chamber | Thick, muscular wall grinds food; feels firm compared with the crop |
| Intestine | gut | Runs the length behind the gizzard, where food is absorbed |
| Circulation, excretion & nerves | ||
| Dorsal blood vessel | main dorsal vessel | The dark line along the top (dorsal) side; carries blood forward |
| Aortic arches | “hearts” | Five pairs of muscular vessels near the front that pump blood — not one heart |
| Nephridia | excretory tubules | Paired in most segments; remove waste — the worm’s “kidneys” |
| Ventral nerve cord | nerve cord | Runs along the bottom (ventral) side; the dorsal vessel sits on top, the nerve cord below |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Instrument handling & safe technique | Grips the scalpel, scissors, forceps, or probe awkwardly; cuts too hard or too deep; puts hands or specimen at risk. | Holds the instruments correctly with reminders and cuts more carefully, but still presses too hard or steadies the specimen poorly. | Holds each instrument the right way and makes shallow, controlled cuts, working safely for both the student and the specimen. |
| Careful exposure & observation | Cuts before looking and tears or destroys structures while opening the specimen. | Opens the specimen roughly along the correct line but disturbs organs before observing them. | Opens the specimen cleanly along the dorsal midline without damaging structures, and observes the layout before disturbing anything. |
| Locating & naming external structures | Cannot point to the clitellum, segments, or setae, or tell anterior from posterior. | Finds a few external landmarks with prompting but confuses dorsal and ventral or miscounts segments. | Locates and names the clitellum, segments, and setae on the specimen and orients it correctly by anterior/posterior and dorsal/ventral. |
| Locating & naming internal structures | Guesses at the organs or names the wrong ones once the specimen is open. | Finds the larger organs but cannot reliably distinguish crop from gizzard or trace the blood vessel and nerve cord. | Locates and names the dorsal blood vessel, aortic arches, crop, gizzard, intestine, seminal vesicles, nephridia, and ventral nerve cord on the specimen. |
| Explaining structure & function (and specimen care) | Cannot say what a structure does, and lets the specimen dry out or handles it carelessly. | Explains one or two structures' functions but not the rest, and keeps the specimen moist only when reminded. | Explains why key structures do their jobs — the gizzard grinding, the clitellum's role, how segmentation aids movement — while keeping the specimen moist, handling it respectfully, and cleaning up afterward. |
| 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 structure and function together: not just pointing to the gizzard, but saying what it does and why its wall is muscular. Ask “so what does that structure do?”
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 | Instrument handling & safe technique | NY / Appr / Mast | |
| 2 | Careful exposure & observation | NY / Appr / Mast | |
| 3 | Locating & naming external structures | NY / Appr / Mast | |
| 4 | Locating & naming internal structures | NY / Appr / Mast | |
| 5 | Explaining structure & function (and specimen care) | 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.