Use these targets, vocabulary, rubrics, examples, and score sheet with the instructor's approved lesson and procedure. This is an assessment companion, not a complete lesson or safety authorization.
By the end of the Circular Motion & Gravitation unit, a student should be able to:
Five science criteria plus separately reported integration (Page 3).
Whirl a mass, measure the inward force, compare to v²/r.
The student names what supplies the inward force out loud (Page 4).
Radius, period, and measured force kept distinct.
You are making a decision, not adding up points. For each criterion, decide whether the work is Developing, Proficient, or Mastery — the column language tells you which. A criterion counts as mastered only when the student can both take the data and justify it against the physics. Each student has three tokens per term; each token retries one rubric criterion. Approved accommodations, equipment failures, and approved absences are handled separately and do not consume these tokens.
Accept listed synonyms; use the distinction column to resolve near-matches.
| Canonical answer | Accepted synonyms | Common confusion / discriminator |
|---|---|---|
| Circular motion | ||
| Centripetal acceleration | center-seeking acceleration; v²/r | Points toward the center, not along the motion |
| Centripetal force | net inward force | A role filled by a real force, not a new kind of force |
| Period | time per revolution; T | Time per cycle; frequency is its inverse |
| Tangential velocity | speed around the circle | Direction is along the tangent; it constantly changes |
| Gravitation & orbits | ||
| Universal gravitation | Newton's law of gravity | Force falls off as the inverse square of distance |
| Inverse-square law | 1/r² dependence | Double the distance → one quarter the force |
| Mass vs weight | amount of matter vs gravitational force | Mass is constant; weight changes with the field |
| Orbit | continuous free fall | Falling, but moving sideways fast enough to keep missing the ground |
| Criterion | Developing | Proficient | Mastery |
|---|---|---|---|
| Centripetal acceleration & force | Thinks an object in a circle has no acceleration at constant speed. | Knows there is acceleration but points it the wrong way. | Shows centripetal acceleration points to the center, uses v²/r, and explains why speed can be constant while velocity changes. |
| Source of the centripetal force | Invents a "centrifugal force" pushing outward. | Names a real force but not consistently across situations. | Identifies the actual force supplying the centripetal requirement — tension, friction, gravity, or normal — in each case. |
| Universal gravitation | Confuses mass with weight; ignores distance. | Uses the gravitation equation but mishandles the inverse-square. | Applies the inverse-square law correctly and distinguishes mass from weight in any gravitational field. |
| Orbits & satellites | Treats orbit as unrelated to gravity. | Links gravity to orbit but cannot relate speed, radius, and period. | Derives the relationship among orbital speed, radius, and period and explains why an orbit is continuous free fall. |
| Lab technique (centripetal apparatus) | Swings the mass erratically; takes no repeatable data. | Collects data but does not control the radius or period cleanly. | Uses a conical pendulum or centripetal-force apparatus to measure force versus speed and compares to v²/r with uncertainty. |
| Integration (cross-domain) | Makes no supported connection between the source and the science. | Uses the source but needs help connecting evidence, writing, or limitations to the science. | Independently connects History, Reading, and Writing using a cited source, appropriate evidence, a limitation, and a scientific explanation. |
The split between Proficient and Mastery is cause over label: not just saying “centripetal force,” but naming the real force that supplies it. Ask “what would happen if the string snapped?” — it flies off along the tangent, not outward.
Read these before you grade. They show what Mastery and Developing actually sound like, plus the edge cases where you should coach rather than decide on the spot.
Student: ______________________________________ Date: _______________ Guide: _________________________
| # | Criterion | Decision | Notes |
|---|---|---|---|
| 1 | Centripetal acceleration & force | Dev / Prof / Mast | |
| 2 | Source of the centripetal force | Dev / Prof / Mast | |
| 3 | Universal gravitation | Dev / Prof / Mast | |
| 4 | Orbits & satellites | Dev / Prof / Mast | |
| 5 | Lab technique (centripetal apparatus) | Dev / Prof / Mast | |
| 6 | Integration (cross-domain) | Dev / Prof / Mast |
☐ No ☐ Yes — for criterion: __________
Tokens left this term after this session (choose one): ☐ 3 ☐ 2 ☐ 1 ☐ None left
Dev = Developing · Prof = Proficient · Mast = Mastery · Unsure between two levels? Circle the lower one and note what a re-do would need.