Purpose and standards
Essential question: How do Newton's laws connect forces and acceleration? This week's lessons support HS-PS2-1 by using mathematical representations of the force–mass–acceleration relationship, and introduce interacting systems relevant to HS-PS2-2. They do not by themselves establish complete mastery of every aspect of these performance expectations. Students should already understand the Weeks 02–06 velocity, net-force, vector direction and free-body diagram lessons.
Safety and access: All assignments have offline simulation and printable data routes. No pushing people, heavy carts, loaded springs, collisions, vehicles, hazardous ramps or video recording of others is required. Real investigations demand local teacher oversight and safety assessment. The labs generate synthetic outputs, not actual measured readings.
Monday — First Law
Launch: A 4 kg cart has a +6 N right and −6 N left external force sum. Therefore a=0. At v0=3 m/s, over T=2 s its displacement is +6 m under the idealization of unchanging balanced forces. Explain why it is possible to move while net force remains zero.
Teacher probe: Have students separate force arrows from a velocity description and name a realistic slowing force.
Monday lesson →
Tuesday — Second Law
Quantitative exercise: 12 N net to the right on 3 kg gives a=+4 m/s²; the same 12 N on 6 kg gives +2 m/s². With fixed 3 kg, doubling net force doubles acceleration. Emphasize ΣF, not one arbitrarily selected force, and check dimensions: N/kg=m/s².
Misconception: Negative acceleration does not always imply decreasing speed. Ask for an example of leftward velocity and leftward net force.
Tuesday lesson →
Wednesday — Third Law
Demonstration without apparatus: A pushes B right +12 N. B pushes A left −12 N. For the special classroom model where these are the sole horizontal net forces, mA=3 kg gives aA=−4 m/s² and mB=6 kg gives aB=+2 m/s². Two different body boundaries must appear in separate FBDs.
Important: A book's normal and its weight are NOT a third-law pair, even when equal. They both act on the book. The table/book interaction pair consists of table on book and book on table. The gravity interaction pair consists of Earth on book and book on Earth.
Wednesday lesson →
Thursday — Virtual Dynamics Investigation
Procedure: (1) predict acceleration under fixed net force, (2) vary mass, (3) hold mass fixed and vary net force, (4) compare pairs of forces on separate bodies, (5) export model data, (6) explain how friction or an additional force would affect single-body net force.
Results: with +8 N, m=2 kg → +4 m/s² and m=4 kg → +2 m/s². With F interaction=12 N, masses A=3 kg and B=6 kg, respective assumed-only-net horizontal accelerations −4 and +2 m/s².
Thursday lesson →
Friday — Evidence and Correction
Students write claim–evidence–reasoning across all three laws. Require at least two signed SI calculations, clear identification of one body or two interacting bodies, a misconception corrected using evidence, and one clearly stated ideal-model limitation.
Friday offers ten randomized open-book formative questions from a twenty-item bank, with answer explanations and 80% practice corrections. The quiz is publicly readable and not a confidential proctored assessment, midterm, final, or official verified transcript.
Friday lesson →
20-point teacher-reviewed CER rubric
- Claim · 4 points
- Specific, scientifically sound explanation of Newton's laws in the defined frame.
- Evidence · 4
- Two correctly calculated cases with direction and units.
- Diagram · 4
- Body boundaries and force agents identified; third-law pair separated.
- Reasoning · 4
- Explains zero net force, ΣF=ma, and equal opposite interaction forces on distinct bodies.
- Limitations and revisions · 4
- Documents one missing physical factor and a substantive corrected claim.
16/20 = 80% review target. Practice scores are stored locally for student feedback only. Formal exams must be separately controlled and reviewed.
Vocabulary and differentiation
Foundation: labeled force arrows on paper and a table of mass 2, 3, 4, 6 kg; provide positive axis. Use a numerical table in place of graph interpretation when necessary.
Core: calculate two relationships and explain separate action-reaction diagrams independently.
Extension: consider a second external force on either body, explain how its net acceleration changes without violating F(A on B)=−F(B on A), and connect the combined-system internal-force cancellation to the separate FBDs.
Resources and integrity
Newton's Laws Dynamics Studio · Synthetic single-cart data · Synthetic interaction-pair data · Week 06 Force Builder
Do not overwrite or reset existing khae_high_science_evidence_v1: daily fields. New Week 07 practice has a separate namespace and JSON export; it does not sync across devices. All existing dormant STOS files remain untouched.