Students construct and interpret Sankey diagrams, read efficiency and the largest waste from them, and apply efficiency and conservation to compare real energy systems (AC9S9U05, nodes 3 and 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 9 min · Explain 10 min · Evaluate 3 min · Typical adds 3 min, Wider about 2 min
A concept tutorial for introducing or revising the idea. Set the width with ?width=minimum, typical (default) or wider. It closes Year 9 energy, after How much is useful?
Neither is a hinge node. The common slips are reading band widths as unrelated numbers and judging efficiency by the size of the useful band rather than its share of the input. The prediction targets the second.
Board notes: the board draws one split (input to outputs), not multi-stage chains. Power station figures are rounded and typical: coal about 35%, hydro about 90%, solar panels about 20%.
Reading widths as proportions. When a student compares two diagrams by the width of the useful band alone, ask what share of each input band it is.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student's outputs don't add up to the input. | What does conservation of energy say about the total out? | It must equal the total in. The board shows the missing amount. |
| A student says the widest band is the useful one. | Which band carries energy the device was made to produce? | The useful band goes straight on; in a coal station the widest band is waste heat. |
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 power station's waste heat warms a nearby town's homes. Redraw its Sankey diagram. What happens to its overall efficiency? (Some waste becomes useful, so the efficiency of the whole system rises.)
Support: Give a Sankey template with the input band drawn and gaps for each output's label and amount.
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 9 student in Australia. Help me understand the ideas in ONE lesson only, from the lesson "What does a Sankey diagram show?". The ideas: - Sankey diagrams — representing energy inputs, outputs and losses: I can construct and interpret Sankey diagrams to represent energy flow through a system, reading off efficiency and identifying where energy losses occur. - Applying conservation of energy and efficiency to real systems: I can apply the law of conservation of energy and efficiency analysis to evaluate real energy systems and identify where improvements could be made. What understanding looks like: - Reads efficiency and identifies major energy losses from a given Sankey diagram - Constructs a Sankey diagram from energy data with correctly proportioned arrows - Critiques a Sankey diagram — identifies what it represents well and any limitations - Applies conservation of energy to account for all energy inputs and outputs in a real system - Calculates efficiency for a real system and interprets the result - Identifies where energy losses occur and suggests a practical improvement Mistakes students often make here: - A student's outputs don't add up to the input. - A student says the widest band is the useful one. 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 (Efficiency — useful output as a proportion of total input), 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 a Sankey diagram show?".
A wind turbine takes in 500 J of kinetic energy and gives out 200 J of electricity. What is its efficiency, and how would its Sankey diagram show the rest?
200 ÷ 500 × 100% = 40%. The other 300 J would bend away as wasted bands (heat and sound), together as wide as 300 J.
Next: Year 10 energy (climate and the energy balance) uses the same accounting.
In class: draw Sankey diagrams on grid paper (1 square = 10 J) for three appliances from their labels or data sheets.