This packet is everything a parent or guide needs to assess Unit 03 at home — learning targets, the terms that count as correct, the mastery rubric, calibration examples, and a clipboard score sheet. No multiple-choice test: the student shows mastery by building a wet mount at the bench and explaining why each step keeps the field clear.
By the end of the Preparing Wet Mounts unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Build a mount from onion skin, elodea, or pond water at the bench.
The student explains why each step keeps the field clear (Page 4).
Specimen, steps taken, and what a re-do fixed 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 build the mount and justify why each step keeps the field clear. 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 |
|---|---|---|
| Preparing the slide | ||
| Wet mount | temporary slide | A specimen in a water drop under a coverslip — not a dry or permanent slide |
| Coverslip | cover glass | Thin square that flattens the specimen and protects the objective lens |
| Thin section | single-cell layer | Thin enough for light to pass through; a thick chunk stays dark |
| Keeping the field clear | ||
| Water drop | mounting drop | One drop sized to fill just under the coverslip — not a flood |
| Bubble | air pocket | Trapped air that hides the specimen; avoided by lowering at an angle |
| Wicking | drawing off excess | Pulling extra water from one edge with paper toweling |
| Onion epidermis | onion skin | The classic thin plant layer peeled for a first mount |
| Elodea | waterweed leaf | A naturally thin leaf, ready to mount without peeling |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Clean slide handling | Grabs the slide by its faces, leaving fingerprints and smears across the viewing area. | Holds the slide by the edges when reminded but forgets to check it is clean and dry first. | Handles the slide by its edges only, checks it is clean and dry, and keeps the viewing area free of prints and dust. |
| Placing a thin specimen | Piles on a chunk of specimen too thick for light to pass through. | Chooses a thin piece but centers it poorly or lets it fold over. | Selects or peels a specimen thin enough to see through — a single onion-skin layer or elodea leaf — and lays it flat and centered. |
| Sizing the water drop | Floods the slide or adds no water at all. | Adds water but consistently too much or too little for the coverslip. | Places a single drop sized so it spreads just under the coverslip without overflowing or leaving dry gaps. |
| Lowering the coverslip | Drops the coverslip flat, trapping a field full of air bubbles. | Lowers it at an angle sometimes but still leaves stray bubbles. | Rests one edge of the coverslip in the water and lowers it slowly at a shallow angle so the water spreads bubble-free. |
| Wicking & fixing a bad mount | Leaves excess water pooling or gives up when the mount goes wrong. | Wicks excess water but cannot diagnose why a mount looks bad. | Wicks off excess with paper from one edge, and recognizes a too-thick, too-dry, or bubbly mount and remakes it. |
| 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 technique over luck: a clear field from a sloppy method won’t repeat. Watch the hands — slide held by the edges, one sized drop, coverslip eased down at a shallow angle, excess wicked clean.
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 | Clean slide handling | NY / Appr / Mast | |
| 2 | Placing a thin specimen | NY / Appr / Mast | |
| 3 | Sizing the water drop | NY / Appr / Mast | |
| 4 | Lowering the coverslip | NY / Appr / Mast | |
| 5 | Wicking & fixing a bad mount | 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.