Efficiency, Sankey diagrams, and work done
Calculate energy efficiency as the ratio of useful output energy to total input energy, construct and interpret Sankey diagrams, and calculate work done using work = force × distance
Lesson
Set out your lesson
“Efficiency, Sankey diagrams, and work done means practising the idea at the table with a simple hands-on check. We will demo once, then your child tries.”
Bring to the table
- A small toy car or ball
- A ramp or book stack and a ruler
Extra for the adult
Worked example. A stronger push sends the car farther down the table than a gentle push.
Optional challenge. For Efficiency, Sankey diagrams, and work done, add one harder example after success.
What to notice. Keep one parent note: examples tried; results; support used. This session samples Efficiency, Sankey diagrams, and work done, not mastery.
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1 approach
Efficiency, Sankey diagrams, and work done means practising the idea at the table with a simple hands-on check. We will demo once, then your child tries.
Materials: A small toy car or ball; A ramp or book stack and a ruler. 1. Say the goal of Efficiency, Sankey diagrams, and work done in plain words once. 2. Adult gives one gentle push and one stronger push, then compares how far the object travels. 3. Child tries three push or pull trials and records which force made a bigger change. 4. Fresh check: one fresh push/pull comparison. Record and stop. Done: three recorded trials with a clear force comparison. Proof: parent note of examples and results. Stop: End after the fresh check; keep optional challenge for another day.
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Practice this concept
Start practiceEfficiency, Sankey diagrams, and work done practice
Practice key ideas from Efficiency, Sankey diagrams, and work done.
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Learning resources
Extra practice links — they do not replace Gakuva’s teaching approach.
PhET Interactive Simulations · Practice link — not the full lesson
Energy Forms and Changes
Before you open · source notes
Energy Forms and Changes supports hands-on exploration for Efficiency, Sankey diagrams, and work done. Not every lab worksheet.
Free interactive page, no sign-in required for the tested path.
Before you openAsk the learner what they changed in the sim or page and what they observed.
Opening this link does not save learning or assess mastery.
Source, access and review notes
Public PhET Interactive Simulations page. An anonymous GET on 2026-11-12 returned HTTP 200 with no login or payment prompt for this URL. Opening the link does not save practice or assess mastery. An adult should preview and guide the learner.
PhET Interactive Simulations. “Energy Forms and Changes.” External page; Gakuva does not copy, host, embed, or redistribute materials.
Unknown — link only
Check understanding
- Calculates efficiency as a percentage from given input and useful output energy values
- Draws a Sankey diagram to represent energy transfers in a device, with arrow widths proportional to energy amounts
- Uses W = Fd to calculate work done when a force moves through a distance
- Identifies which energy transformations in a Sankey diagram are useful and which are wasted
“If your child heard that a light bulb is 10% efficient and uses 60 J of energy, could they work out how much of that energy actually becomes light — and where the rest goes?”
Curriculum record
- Type
- Procedural
- Subject
- Science
- Domain
- Energy
- Age range
- Ages 12–13
Standards