Newton’s Motion

Overview

Students explore how forces cause changes in motion using Newton’s laws. They use a PhET simulation to test predictions, then connect their observations to clear explanations and a short formative check aligned to NSW outcomes for explaining motion using Newton’s laws.

Learning intentions

• Students will describe how forces affect an object’s motion using Newton’s laws.
• Students will use observations from a PhET simulation to support scientific explanations.
• Students will plan and follow a fair test within the simulation by changing one variable at a time.
• Students will represent and interpret results (e.g., motion changes) using simple notes and graphs/tables when relevant.

Success criteria

• I can state what happens to an object’s motion when forces are balanced vs unbalanced.
• I can explain acceleration in terms of net force.
• I can use simulation evidence to justify my claims (not just guesses).
• I can follow a safe and valid approach to investigation by keeping conditions consistent and recording what I changed.

Curriculum links

• SC5-WAM-02 — Students explain the motion of objects using Newton’s laws of motion.
• SC5-WS-04 — Students follow a planned procedure to undertake safe, ethical, valid and reliable investigations (applied to simulation testing and recording).
• SC5-WS-05 — Students select and use tools to process and represent data (e.g., recording observations, constructing a simple table/graph in notes).
• SC5-WAM-01 — Students describe features and applications of different forms of waves (used only as a quick comparison reminder: today focuses on motion, not waves).

Lesson structure (60 minutes)

1. 0–5 min · Hook with problem. Teacher shows the introduction slides and asks: “If two students push the same cart—one hard for a short time, one gently for longer—how could motion end up looking similar or different?” Students write a one-sentence prediction.

2. 5–12 min · Direct teach: Newton’s motion ideas. Teacher uses the introduction slides to recap: balanced forces → no change in motion; unbalanced net force → acceleration; action–reaction forces occur in interacting bodies. Students complete a quick “my claim + evidence” sketch in notebooks (no simulation yet).

3. 12–18 min · Simulation setup and investigation plan. Teacher distributes the forces-and-motion PhET investigation worksheet and replays instructions on the introduction slides. Teacher models choosing a single variable: e.g., change one applied force while keeping mass constant. Students, in pairs, identify:

• independent variable (what they will change),
• dependent observation (what they will record: acceleration/change in velocity),
• control variable(s) (what they will keep the same).

4. 18–30 min · Guided exploration 1 (net force). Teacher directs students to run PhET for the “net force / forces and motion” scenario (same sim for all). They must test three cases: balanced forces (net force = 0), small unbalanced force, larger unbalanced force. Teacher circulates using prompts shown on the introduction slides. Students record in the forces-and-motion PhET investigation worksheet: for each case, what happens to speed and direction, and a one-line Newton’s-law explanation.

5. 30–38 min · Class discussion: connect evidence to laws. Teacher pauses the class and uses the introduction slides to ask:

• “What did you observe about acceleration when net force was zero?”
• “How did acceleration change as net force increased?” Students share one paired result and link it to the relevant law in a full sentence.

6. 38–48 min · Guided exploration 2 (mass vs force). Teacher returns to the introduction slides and sets a new challenge: keep force the same, change mass (light vs heavy). Students predict before running the sim, then record results and update their explanation in the forces-and-motion PhET investigation worksheet. Teacher checks for valid procedure: students should only change mass, not also the applied force.

7. 48–55 min · Formative assessment: quick explanation check. Teacher uses the introduction slides to present a short scenario: “A 2 kg trolley and a 4 kg trolley experience the same unbalanced force. Compare their accelerations and justify using Newton’s laws.” Students answer individually (2–3 minutes) in the space on the forces-and-motion PhET investigation worksheet or on a half-page response.

8. 55–60 min · Plenary and exit. Teacher takes two examples from the class, then summarises key statements on the introduction slides. Students do a quick exit ticket: “One sentence: How do balanced/unbalanced forces change motion?” Collect the forces-and-motion PhET investigation worksheet.

Resources

• the introduction slides
• the forces-and-motion PhET investigation worksheet
• Devices for PhET access (1 per pair, or teacher projection + pair stations)
• Student notebooks and pens
• Timer for simulation phases
• Data-recording table on the forces-and-motion PhET investigation worksheet

Assessment

• Formative during guided exploration: teacher checks students’ recorded net force cases and whether only one variable was changed.
• Formative at 48–55 min: scenario response assesses correct use of Newton’s laws and evidence-based reasoning.
• Exit ticket at 55–60 min checks consolidation of balanced vs unbalanced forces and motion change.

Differentiation

• Support: Provide sentence starters on the forces-and-motion PhET investigation worksheet (e.g., “When net force is zero, the trolley… because…”).
• Support: Offer a worked example of how to fill one row of the investigation table.
• Extension: Students predict a “middle case” (e.g., between two forces) before testing, then explain whether results match the trend.
• EAL/SEN: Use clear visual cues in the worksheet (headings for independent/dependent/control) and accept explanation using drawings plus short sentences.