Students explain that unbalanced forces change motion (starting, speeding up, slowing down, stopping, reversing and changing direction) and represent each change with a force diagram (AC9S7U04, node 3).
Load these into Waypoints Prepare: choose Load URL and paste the copied address, or download the file and import it. In Prepare, the worksheet's Teacher edition shows the answers; the student copy hides them.
Engage and Explore 8 min · Explain 10 min · Evaluate 3 min · Typical adds 4 min, Wider about 4 min
A concept tutorial for introducing or revising the idea; it does not replace trolleys, force meters and ramps. Set the width with ?width=minimum, typical (default) or wider.
Not a hinge node, but its misconception is common: students apply "unbalanced force" to speeding up and miss slowing down, reversing and turning (and often think a backward force can only stop things). The Explore board shows one steady force slowing, stopping and reversing the puck. It builds on node 2 (Balanced), so set that first.
Board notes: the puck slides on frictionless ice and moves left and right only; turning and falling are covered by the sort and the round-the-bend question, not the board. Speeds below zero on the graph mean moving to the left. The Typical board has friction that matches the push up to 4 N while the box is still.
Seeing slowing, stopping, reversing and turning as changes that need an unbalanced force. When a student says the puck ran out of force, ask what it would do on ice with no push at all.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student says the puck turned round because it ran out of force. | On ice with no push at all, what would the puck do? | Keep sliding at the same speed. Moving needs no force; changing the motion does. The push changed it. |
| A student says the car on the roundabout has balanced forces because its speed is steady. | Is it going in a straight line? | No: its direction changes, so its motion changes, so the forces are unbalanced (the road pulls it towards the centre). |
| A student thinks a force only acts while the object moves in its direction. | When did the speed start falling on the graph? | The moment the push started: the force acts whichever way the puck is moving. |
One possible solution for each task. Other correct programs are fine.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Stretch: A ball is thrown straight up. At the very top it is still for an instant. Is the force on it balanced at that moment? (No: weight still acts, which is why it falls.)
Support: Give the sentence frame: 'The net force points … so the object … (speeds up, slows down, turns) …'.
For a student who has done the lesson and is still stuck. They paste it into an AI tool your school allows; it asks questions about this lesson's one idea and doesn't give answers. Students see it on the course recap page only through a link ending in ?coach=1: recap with coach prompts.
You are a patient science coach for a Year 7 student in Australia. Help me understand ONE idea only, from the lesson "What does an unbalanced force do?". The idea: Unbalanced forces and changes in motion: I can explain that unbalanced forces cause a change in motion and represent this with force diagrams. What understanding looks like: - States that unbalanced forces cause a change in motion - Gives 2 examples with correct force diagrams - Identifies both speed and direction as possible changes Mistakes students often make here: - A student says the puck turned round because it ran out of force. - A student says the car on the roundabout has balanced forces because its speed is steady. - A student thinks a force only acts while the object moves in its direction. How to coach me (rules from the Waypoints Kit coach): - Ask me one short question at a time (2 to 4 sentences) and wait for my answer. Never give me the answer before you have heard my thinking, and don't hide the answer inside your question. - Start in Discover: ask me to explain the idea in my own words, or to predict what happens in a simple example. I can switch any time: "teach it back" (you play a beginner and I explain), "spot the flaw" (you show me an answer with one common mistake and I find it), or "check" (I explain, and you tell me what is solid and what to revisit). - If I am stuck or say "just tell me", ask what I think first, then give a small hint or a simpler example. Explain only after I have had a real go. - If I seem to be missing the idea that comes before this one (Balanced forces and equilibrium), check it quickly, then come back. - Stay in this idea: don't teach later ideas or add extra content. If I ask about something else, say it is for another lesson and bring me back. - After you help, ask me one reflective question, such as how I know my answer is right or what I would check. - Praise my effort and method, not my ability. - You can be wrong: if I rely on something you said, remind me to check it against my notes or the lesson. If you don't know, say so. - Use simple words. - Stop when I can explain the idea in my own words and get one new example right. Then tell me to go back to the lesson "What does an unbalanced force do?".
A netball flies towards the ring and bounces back off the backboard. Give the change in motion and the force that caused it.
It reversed direction (and slowed, then sped up the other way). The backboard pushed it back: an unbalanced force away from the board.
Next: gravity, mass and weight (node 4). Node 5 (force, mass and the size of the change) is a class task: see the unit primer. In Year 10 this becomes Newton's first and second laws.
In class: a trolley pulled by a force meter, then released against a rubber band; a ball rolled across the floor and tapped sideways with a ruler (a change of direction only).
The spearthrower question (Wider) is general. For richer context, use local resources and community guidance about spearthrowers in your region.