This packet is everything a parent or guide needs to assess Unit 08 at home — learning targets, the answers that count as correct, the mastery rubric, calibration examples, and a clipboard score sheet. No multiple-choice test: the student shows mastery by predicting whether an object floats and measuring the buoyant force to prove it.
By the end of the Fluids & Pressure unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Measure the buoyant force; compare to displaced fluid.
The student predicts float or sink and explains why (Page 4).
Weights, displaced volume, and buoyant force 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 take the measurement and defend why it floats. 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 |
|---|---|---|
| Density & pressure | ||
| Density | mass per volume | A property of the material — not the same as total mass |
| Pressure | force per area | The same force on a smaller area is more pressure |
| Pressure with depth | hydrostatic pressure | Rises with depth because of the weight of fluid above |
| Pascal's principle | pressure transmits equally | Pressure on a confined fluid is passed on undiminished |
| Buoyancy & flow | ||
| Buoyant force | upward push of fluid | Equals the weight of the displaced fluid — not the object's weight |
| Archimedes' principle | displaced-weight rule | Floats if the displaced fluid weighs more than the object |
| Continuity | flow-rate conservation | Same flow rate — a narrower channel means faster flow |
| Bernoulli (qualitative) | fast flow, low pressure | Where a fluid speeds up, its pressure drops |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Density & pressure | Confuses mass with density or force with pressure. | Computes each but not how pressure changes with depth. | Relates density and pressure correctly and explains why pressure increases with depth in a fluid. |
| Buoyancy & Archimedes' principle | Thinks heavy things always sink. | States Archimedes' principle but cannot apply it to predict floating. | Predicts float or sink from the weight of displaced fluid and defends the reasoning quantitatively. |
| Pascal's principle | Does not see how pressure transmits through a fluid. | Knows a hydraulic lift multiplies force but not why. | Explains Pascal's principle and how a hydraulic system trades distance for force at equal pressure. |
| Fluid flow | Ignores that speed and area are related in flow. | Recalls that narrowing speeds flow but not the pressure consequence. | Applies continuity and the qualitative Bernoulli relationship to connect speed, area, and pressure in a moving fluid. |
| Lab technique (buoyancy measurement) | Estimates buoyancy by eye with no measurement. | Weighs an object in and out of water but does not compare to displaced volume. | Measures the buoyant force and the displaced fluid and verifies Archimedes' principle with uncertainty. |
| 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 displaced fluid: a mastered student explains floating by the weight of water pushed aside, not by “heavy” or “light.” Ask “how much water does it push aside, and what does that weigh?”
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 | Density & pressure | NY / Appr / Mast | |
| 2 | Buoyancy & Archimedes' principle | NY / Appr / Mast | |
| 3 | Pascal's principle | NY / Appr / Mast | |
| 4 | Fluid flow | NY / Appr / Mast | |
| 5 | Lab technique (buoyancy measurement) | 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.