Unit 04 · Forces & Motion
This unit gets things moving and asks why. You measure speed as distance over time, read motion off a distance–time graph, and learn what a force really does — a push or a pull that can start, stop, speed up, or turn an object. When the forces on something are balanced, its motion doesn’t change; when they’re unbalanced, it does. Newton’s three laws tie it all together. Mastery means you can measure motion at the bench and explain it with the forces behind it.
| Criterion | Developing | Proficient | Mastery |
|---|---|---|---|
| Speed & distance–time | Confuses speed with distance or with time. | Measures speed but mixes up the units. | Measures distance and time, calculates speed, and reads it off a distance–time graph. |
| Forces: pushes & pulls | Cannot say what a force does. | Calls a force a push or pull but cannot spot one acting. | Identifies forces and their directions, and measures a force with a spring scale using correct units. |
| Balanced vs. unbalanced forces | Thinks a still object has no forces on it. | Defines balanced forces but cannot predict the motion. | Predicts changing motion from a net force; explains that balanced forces allow rest or constant velocity. |
| Newton's three laws | Cannot state a law of motion; thinks a moving thing needs a constant push to keep going. | Recites a law but cannot give a real example. | Explains each of Newton's three laws with a real example from the ramp or the bench. |
| Lab technique (motion on a ramp) | Releases the cart carelessly or mistimes the run. | Collects times but with inconsistent starts. | Rolls a cart down a ramp, times it cleanly, and links the measured motion to the force behind it. |
| 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. |
Integration is reported separately and cannot lower the science grade or block a science demonstration pass. Science and practical criteria determine that pass. Use the integration guide's evidence checklist for the separately reported criterion.
“I rolled the cart down the ramp and timed it over a set distance to find its speed. It kept speeding up because gravity pulled it — an unbalanced force. On the flat table it slowed and stopped, not because it ‘ran out of push,’ but because friction pushed back against it.”
“The cart went faster because… it wanted to? It stopped on the table because it ran out of speed. Heavier carts fall faster, right?”
You demonstrate this unit through hands-on measurement — timing a cart on a ramp, reading its speed off your data, and measuring forces with a spring scale — plus short oral checks where you explain the motion aloud, not a multiple-choice test. A criterion counts as mastered only when you can both take the measurement and explain it with a force. 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.