Unit 02 · Skeletal & Muscular Systems
This unit builds the body’s framework and its movers: the axial and appendicular skeleton and the major bones, how joints classify by the movement they allow, the three muscle types and the major muscle groups, and how muscles pull — never push — in antagonistic pairs to move the skeleton. Mastery means you can find a bone, muscle, or joint on a model or skeleton and defend the call from its structure, not just recognize a labeled diagram.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Axial vs. appendicular skeleton & major bones | Cannot sort the skeleton into axial and appendicular, or cannot name the major bones. | Names major bones but cannot sort them into axial vs. appendicular, or slips on bone structure. | Sorts bones into axial and appendicular, names the major bones on a skeleton, and describes bone structure — compact and spongy bone, marrow. |
| Joint types & movements | Cannot name a joint type or a movement it allows. | Names joint types from a list but cannot match a movement to the joint on a model. | Classifies the major joint types — hinge, ball-and-socket, pivot, gliding — and demonstrates the movement each allows on a skeleton or model. |
| The three muscle types & major muscle groups | Cannot name the three muscle types, or mixes them up. | Names skeletal, cardiac, and smooth muscle but cannot say where each is found or name the major muscle groups. | Names the three muscle types with where each is found and identifies the major muscle groups on a torso model. |
| How muscles pull — antagonistic pairs | Thinks muscles push, or cannot pair a mover with its antagonist. | Knows muscles pull and names an antagonistic pair but cannot explain how a contraction shortens the muscle. | Explains that muscles pull and never push, pairs a mover with its antagonist, and describes contraction as filaments sliding to shorten the muscle. |
| Lab technique (model / skeleton ID defense) | Cannot locate a requested bone, muscle, or joint on the model or skeleton. | Points to a bone, muscle, or joint on the model but cannot defend the call from its structure. | Identifies a bone, muscle, or joint on a model or skeleton and defends the call by linking its structure to what it does. |
| 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. |
“This is the biceps brachii — it crosses the front of the elbow, so when it shortens it pulls the forearm up and the elbow flexes. It can’t push the arm back down; that’s the triceps on the other side pulling the opposite way. The two are an antagonistic pair.”
“It’s an arm muscle. It makes the arm move. The bones are… the long one and the two little ones?”
You demonstrate this unit through model and skeleton identification labs — locating a bone, muscle, or joint and defending it aloud — plus short oral checks where you explain how a muscle pulls, not a multiple-choice test. A criterion counts as mastered only when you can both find the structure on the model and justify the anatomy behind it. 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.