This packet is everything a parent or guide needs to assess Unit 02 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 drawing correct free-body diagrams and predicting motion from the forces.
By the end of the Dynamics & Newton's Laws unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Measure forces with an Atwood machine or force table, then check the prediction.
The student draws and defends a free-body diagram aloud (Page 4).
Diagrams, predictions, and measured forces 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 draw the diagram and justify the physics behind it. 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 |
|---|---|---|
| Newton's laws | ||
| Inertia | resistance to change in motion | Depends on mass alone, not on speed |
| Net force | sum of forces; ΣF | Zero net force means constant velocity, not necessarily rest |
| Newton's second law | F = ma | Acceleration follows the net force, not the velocity |
| Newton's third law | action–reaction pair | The pair acts on two different objects, so it does not cancel |
| Forces & friction | ||
| Free-body diagram | force diagram | Show only the real forces — no “force of motion” |
| Normal force | support force; N | Perpendicular to the surface; not always equal to weight |
| Friction | static vs kinetic | Depends on the normal force, not on surface area or speed |
| Weight vs mass | mg vs amount of matter | Weight is a force in newtons; mass is the amount of matter |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Newton's three laws | Recites the laws but applies them to the wrong situations. | States each law but confuses inertia with the second law. | Applies the right law to each situation and explains why an object at constant velocity has zero net force. |
| Free-body diagrams | Adds phantom forces (like "the force of motion") or omits real ones. | Draws most forces but misplaces the normal force on an incline. | Draws complete, correct free-body diagrams for any object, including inclines and connected systems. |
| Net force & acceleration (F = ma) | Adds force magnitudes without regard to direction. | Finds net force on flat ground but stalls on inclined-plane components. | Resolves forces into components and solves for acceleration on flat and inclined surfaces. |
| Friction | Thinks friction depends on surface area or speed. | Uses the friction equation but confuses static and kinetic. | Distinguishes static from kinetic friction and relates each correctly to the normal force. |
| Lab technique (force measurement) | Misreads the spring scale or ignores the string's mass assumptions. | Takes readings but does not check the system against prediction. | Uses an Atwood machine or force table to measure forces cleanly and compares result to prediction 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 only real forces: not just listing forces, but drawing the ones that are actually there and resolving them into components. Ask “which force causes that acceleration?”
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 | Newton's three laws | NY / Appr / Mast | |
| 2 | Free-body diagrams | NY / Appr / Mast | |
| 3 | Net force & acceleration (F = ma) | NY / Appr / Mast | |
| 4 | Friction | NY / Appr / Mast | |
| 5 | Lab technique (force 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.