Students define a mixture, explain that its parts keep their properties, vary in amount and can be separated physically, and distinguish mixtures from compounds (AC9S8U06, node 4).
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 7 min · Explain 10 min · Evaluate 3 min · Typical adds 4 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 Why isn't salt poisonous? (compounds) and links back to Year 7 separating mixtures.
Not a hinge node, but the element–compound–mixture distinction is where Year 8 students most often slip: "air is a compound", "a mixture has fixed amounts", "anything with two kinds of atom is a compound" (humid air). The prediction and the Wider step target these.
Board notes: gases in a box, enlarged and in 2D; air's proportions are rounded (about 78% nitrogen, 21% oxygen, 1% argon, a trace of carbon dioxide). The dissolve board's salt particles stand for sodium and chloride ions.
Telling a mixture from a compound when both contain two kinds of atom. Ask 'are the different atoms joined in one particle, or in separate particles?' and let the student look before answering.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student says air is a compound. | Is any nitrogen atom joined to an oxygen atom on the board? | No: they are separate particles, mingled. Different substances not joined make a mixture. |
| A student thinks a mixture has a fixed recipe. | Is weak cordial still cordial? | Yes. A mixture's parts can be in any amounts; only compounds have a fixed ratio. |
| A student says humid air is a compound because it contains water. | Is the water joined to the nitrogen? | No. It is a mixture that happens to include a compound. |
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.
Open task: any program that does what the step asks.
Stretch: Brass is a mixture of copper and zinc in different amounts for different uses. Why can it be called a mixture, even though it looks like one metal? (The atoms are mingled, not in a fixed ratio, and each metal's atoms are unchanged.)
Support: Give the three questions as a checklist: Joined? Fixed amounts? Separated physically?
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 "Mixed, not joined?". The idea: Mixtures — substances physically combined, properties retained: I can define mixtures, explain that components retain their properties and can be separated by physical means, and distinguish mixtures from compounds. What understanding looks like: - Defines a mixture and gives examples of solutions, suspensions and colloids - Explains that mixture components retain their individual properties - Identifies at least two differences between a mixture and a compound Mistakes students often make here: - A student says air is a compound. - A student thinks a mixture has a fixed recipe. - A student says humid air is a compound because it contains water. 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 (Compounds — different atom types chemically combined), 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 "Mixed, not joined?".
Iron and sulfur are mixed, then heated to make iron sulfide. Which is the mixture and which the compound, and how could you tell with a magnet?
Before heating: a mixture (a magnet pulls out the iron). After: iron sulfide, a compound (the iron is joined to sulfur, so a magnet can't pull it out).
Next: Symbols, formulas or models? (representations, node 5).
In class: iron filings and sulfur mixed (a magnet separates them) versus heated to iron sulfide (it doesn't); making and evaporating salt water.