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 | Developing | Proficient | Mastery |
|---|---|---|---|
| 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) | Makes no supported connection between the source and the science. | Uses the source but needs help connecting evidence, writing, or limitations to the science. | Independently connects History, Reading, and Writing using a cited source, appropriate evidence, a limitation, and a scientific explanation. |
Integration is reported separately and cannot lower the science grade or block a science demonstration pass. Science and practical criteria determine that pass. Use the integration guide's evidence checklist for the separately reported criterion.
“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.