Students state the new substance test for chemical change, explain it as atoms rearranging into new particles, and use it in place of the reversibility rule (AC9S8U07, node 2, a hinge node).
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 5 min
A concept tutorial for introducing or revising the idea; it does not replace practical work. Set the width with ?width=minimum, typical (default) or wider.
The hinge risk is the reversibility rule from AC9S6U04. Present the new substance test as a replacement, not an addition, and name the counterexamples (dissolving; recharging a battery).
Using 'is it a new substance?' instead of 'can it be reversed?'. When a student calls dissolving chemical, ask how they could get the salt back.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student says boiling is chemical because of the bubbles. | What are the bubbles made of? | Steam: water as a gas. Same substance, so physical. Bubbles are a clue, not proof. |
| A student says dissolving is chemical because the salt disappears. | How could you get the salt back? | Evaporate the water. The salt particles were there all along, spread out. |
| A student says burning destroys the fuel. | Where did the carbon atoms go on the board? | Into carbon dioxide. Atoms are rearranged, never destroyed. |
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: Is cooking pasta a chemical change? What would you look for to decide?
Support: Give the test as a sentence frame: 'Is there a new substance? I think … because …'.
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 "Is it a new substance?". The idea: Chemical change — new substance formation at the particle level: I can explain chemical change as the formation of new substances through bond breaking and forming, and apply the new substance criterion to classify changes. What understanding looks like: - States that new substance formation is the criterion defining chemical change - Correctly classifies at least three changes using the new substance criterion - Explains why reversibility alone is not a reliable criterion using a named counterexample Mistakes students often make here: - A student says boiling is chemical because of the bubbles. - A student says dissolving is chemical because the salt disappears. - A student says burning destroys the fuel. 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 (Physical change at the particle level — rearrangement without new substance), 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 "Is it a new substance?".
Is rusting physical or chemical? How do you know?
Chemical: rust (iron oxide) is a new substance with different properties from iron.
Next in the unit: indicators of chemical change (node 3) and energy in reactions (nodes 4 and 5).
In class: steel wool in vinegar (rust over a few days), and dissolving then evaporating salt water, side by side.