Students explain physical change as the same particles rearranged, spread out or packed together, with no new substance formed, and represent it with the particle model (AC9S8U07, node 1).
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 3 min, Wider about 3 min
A concept tutorial for introducing or revising the idea. Set the width with ?width=minimum, typical (default) or wider. It comes after Elements and compounds and before Is it a new substance? (chemical change, node 2), which uses the same boards to compare.
Not a hinge node, but its misconceptions return in chemical change: boiling splits water into hydrogen and oxygen; particles expand when heated; dissolved substances are destroyed. The prediction tests the first.
Board notes: the heat board shows water's particles as single dots (not their atoms); the steam board shows each particle's atoms. Real steam is invisible; the white cloud above a kettle is tiny drops of liquid water. The dissolve board's salt particles stand for sodium and chloride ions.
Keeping particles the same size. When a student draws bigger particles in steam, ask what grew: the particles or the gaps.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student says the particles get bigger when water boils. | On the board, did the dots get bigger or the gaps? | The gaps. The particles stay the same size; they move faster and spread out. |
| A student says dissolving is a chemical change because the salt disappears. | If you evaporate the water, what is left? | The salt. Its particles were spread out, not changed. |
| A student says bubbles always mean a new substance. | What is inside a bubble in boiling water? | Steam: water particles. Bubbles are only a clue to a chemical change, not proof. |
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.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Stretch: Why does a puddle dry up on a warm day without boiling? (Some particles at the surface have enough energy to escape: evaporation. Still water particles, still a physical change.)
Support: Give the frame: 'In … the particles … but each particle is still … , so no new substance is made.'
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 8 student in Australia. Help me understand ONE idea only, from the lesson "Same particles, new look?". The idea: Physical change at the particle level — rearrangement without new substance: I can explain physical change as rearrangement of particles without formation of new substances, and represent this using the particle model. What understanding looks like: - Explains physical change as particle rearrangement without formation of new substances - Represents a physical change using a particle diagram showing no new substance - Explains why reversibility is a consequence of physical change, not the definition Mistakes students often make here: - A student says the particles get bigger when water boils. - A student says dissolving is a chemical change because the salt disappears. - A student says bubbles always mean a new substance. 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. - 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 "Same particles, new look?".
Wax melts on a candle and drips. Use particles to explain why this is a physical change.
The wax particles move from fixed positions to sliding past each other, but each particle is still wax: no new substance, so physical.
Next: Is it a new substance? (chemical change, node 2), which uses the melting and dissolving boards again to compare with a reaction.
In class: melting chocolate or wax, condensation on a cold can, dissolving and recovering salt by evaporation; weigh ice in a sealed bag before and after melting.