Unit 03 · The Grasshopper
This is your first arthropod, and its whole body is worn on the outside. After the earthworm’s soft body, the grasshopper asks for a lighter, more careful hand: a hard exoskeleton to work through, small external parts to expose and observe without breaking, and mouthparts to tease apart under close view. The work is technique and careful observation — clearing the wings and legs cleanly, looking before you disturb anything, then locating and naming structures and explaining what each one does. An instructor watches you work, and the specimen — exposed cleanly, structures intact — is the proof.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Instrument handling & safe technique | Grips the scalpel, scissors, forceps, or probe awkwardly and cuts too hard through the hard body, crushing parts or slipping. | Handles the instruments correctly with reminders but still presses too hard on the exoskeleton or steadies the small specimen poorly. | Holds each instrument the right way and works with a light, controlled hand suited to a small, hard-bodied specimen, safely for both the student and the specimen. |
| Careful exposure & observation | Tears at the wings and legs and pulls parts off before looking at how they attach. | Removes the wings and legs roughly and disturbs external parts before observing them. | Clears the wings and legs cleanly at their joints and observes each region before disturbing it, leaving the exposed structures intact. |
| Locating & naming external structures | Cannot point to the head, thorax, or abdomen, or find the compound eyes, antennae, or spiracles. | Finds the major body regions with prompting but confuses the mouthparts, misses the spiracles, or overlooks the tympanum. | Locates and names the head, thorax, abdomen, compound eyes, antennae, mouthparts, spiracles, wings, legs, and tympanum on the specimen. |
| Locating & naming mouthpart & internal structures | Guesses at the mouthparts or names the wrong ones once they are separated. | Separates the mouthparts but cannot reliably tell mandibles from maxillae or find the crop and gastric caeca. | Locates and names the mandibles, maxillae, and labium, and finds the crop and gastric caeca on the specimen. |
| Explaining structure & function (and specimen care) | Cannot say what a structure does, and handles the fragile specimen carelessly or lets it dry out. | Explains one or two structures' functions but not the rest, and keeps the specimen moist and intact only when reminded. | Explains why key structures do their jobs — the exoskeleton for support and protection, the spiracles for taking in air, the mouthparts specialized for chewing — while handling the specimen respectfully, keeping it moist, 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. |
“These three regions are the head, thorax, and abdomen. The big compound eyes and the antennae are on the head, and along the abdomen are the spiracles — that’s how it breathes, since air goes straight in through them, not through lungs. I teased the mouthparts apart: these hard ones are the mandibles for chewing, and the exoskeleton is stiff because it has to support the body from the outside.”
“I think these are the eyes? I pulled the legs and wings off before I really looked, so I’m not sure where they went. That hard part is… the shell?”
You demonstrate this unit by doing the dissection while an instructor watches — exposing, locating, and naming real structures and explaining their function on your own specimen, not a written test. A criterion counts as mastered only when you can perform the technique cleanly and identify and explain the structures on the actual specimen. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.