Unit 05 · Fish & Amphibians
This unit follows the vertebrate story from open water toward the shore. Fish come in three grades — jawless lampreys and hagfish, the cartilaginous sharks and rays, and the huge bony-fish radiation — and all of them solve life in water with gills, fins, and, in the bony fish, a swim bladder for buoyancy. Then the unit crosses the hardest threshold in the story: the move onto land, and the amphibians that still live with one foot in each world — metamorphosis from a gilled larva to an air-breathing adult, a dual life in water and on land, and thin, permeable skin that both breathes and leaks. Mastery means you can read a vertebrate’s body as a set of answers to the demands of its habitat.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Jawless, cartilaginous & bony fish | Treats all fish as one kind of animal. | Names the groups but places examples in the wrong one. | Sorts a lamprey, a shark, and a perch by jaw and skeleton and gives a defining trait for each grade. |
| Gills, fins & the swim bladder | Cannot say how a fish breathes or stays off the bottom. | Names the structures but not what each one does. | Explains how gills extract oxygen, fins steer and drive, and the swim bladder controls buoyancy. |
| The move onto land | Sees no difference between living in water and on land. | Names a challenge of land but not how animals met it. | Explains the problems of leaving water — gravity, drying out, breathing air — and how the first tetrapods began to solve them. |
| Amphibian dual life & metamorphosis | Thinks an amphibian is just a kind of fish or reptile. | Knows amphibians change form but overlooks the skin or the water tie. | Explains metamorphosis from gilled larva to adult, the dual life in water and on land, and why permeable skin ties amphibians to moisture. |
| Lab technique (dissection & observation) | Damages the specimen or records no structures. | Dissects or observes carefully but misnames a key structure. | Dissects a bony fish or observes an amphibian, locating gills, fins, or skin structures and recording them in a field notebook. |
| 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. |
“A shark is a cartilaginous fish — no bone, no swim bladder, so it has to keep swimming to stay up — where a perch is a bony fish that hangs still because its swim bladder does the work. A frog started life as a gilled tadpole and metamorphosed into an air-breather, but its thin skin still has to stay wet, which is why it never gets far from water.”
“Fish are all pretty much the same. A frog is basically a lizard. Gills are for swimming, right?”
You demonstrate this unit through a bony-fish dissection or amphibian observation where you locate gills, fins, and skin structures and explain how each fits the animal’s habitat aloud — not a multiple-choice test. A criterion counts as mastered only when you can both handle the specimen and explain the body plan behind what you find. 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.