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# Transfer or transformation?

Year 8 Physics · Energy transfer and transformation

<!-- Speaker note: Students distinguish energy transfer (same type, new place) from transformation (type changes), describe common transformations, and identify by-product heat (AC9S8U05, nodes 3 and 4; node 4 is a hinge). About 25 minutes (Engage and Explore 8 min · Explain 10 min · Evaluate 3 min · Typical adds 3 min, Wider about 3 min). -->

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## Today

**We are learning to** in a transfer, the same type of energy moves from one place to another (heat from a hot drink into your hands). In a transformation, energy changes type (chemical energy in a battery becomes electrical, then light). Almost every transformation also makes some heat that isn't wanted: a by-product.

- I can tell an energy transfer from a transformation.
- I can describe the transformations in a torch or a speaker.
- I can name the by-product heat in a transformation.

<!-- Speaker note: Before class: A concept tutorial for introducing or revising the idea. Set the width with `?width=minimum`, `typical` (default) or `wider`. It follows Moving or stored? and comes before Follow the energy. Node 4 is a hinge: by-product heat is what Year 9 efficiency and Sankey diagrams are built on. Students who think a device makes only its useful output can't account for all the energy later. The prediction targets that. Board notes: the flow diagram board checks each stage's useful energy type and each arrow (transfer if the type is the same, transformation if it changes), then shows the by-products. Sound counts as kinetic (vibrating particles), as in the progression. Teacher: In your own words: the torch flow diagram with a by-product arrow. -->

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## Why it matters

> Touch an old-style light bulb that has been on for a minute and it burns your finger, even though it was only meant to make light.

<!-- Speaker note: Energy comes in two families, kinetic and potential. This lesson follows it as it moves and changes. -->

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<span style="background:#dbeafe; color:#1a1a1a; border:1.5px solid #3b82f6; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">💬 Discussion</span>

## Engage: predict

**A torch bulb is switched on. What kinds of energy come out of it?**

- Only light: that's its job
- Light, and some heat
- Only heat
- Electricity

<!-- Speaker note: What happens: Light, and some heat. Almost every time energy changes type, some of it becomes heat that isn't wanted: a by-product. Old filament bulbs turned most of their energy into heat. Take two or three predictions before anyone runs it. -->

<!-- Speaker note: Teacher: tally the predictions. 'Only light' is the hinge misconception. -->

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<span style="background:#fef3c7; color:#1a1a1a; border:1.5px solid #f59e0b; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✍️ Activity</span>

## Explore it

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fscience%2Fphysics-8%2Ftransform%2Fstep-2&code=widget%3A+energy%0Amode%3A+chain%0Astage%3A+Battery+%7C+chemical%0Astage%3A+Wires+%7C+electrical%0Astage%3A+Bulb+%7C+light+%7C+heat%0A&fresh=1}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/physics-8/transform/?full=step-2#step-2)

<!-- Speaker note:  -->

<!-- Speaker note: Teacher: after Check, ask what the red boxes or arrows had in common. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## What happened?

* Light, and some heat. Almost every time energy changes type, some of it becomes heat that isn't wanted: a by-product. Old filament bulbs turned most of their energy into heat.

<!-- Speaker note: Reveal after running. Ask who predicted it, and what made them think so. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Transfer or transformation

**Transfer (same type, new place) or transformation (type changes)?**

Groups: Transfer · Transformation

Heat from a hot pan into the handle · A moving cue ball hitting another ball and making it move · Sound travelling from a speaker to your ear · A battery lighting a bulb · A ball falling from a shelf · Burning wood

* Answer: Heat from a hot pan into the handle → Transfer; A moving cue ball hitting another ball and making it move → Transfer; Sound travelling from a speaker to your ear → Transfer; A battery lighting a bulb → Transformation; A ball falling from a shelf → Transformation; Burning wood → Transformation

<!-- Speaker note:  -->

<!-- Speaker note: Teacher: the sort and the by-product questions are the success criteria. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## By-products

**A bulb makes light and heat. Which is the by-product?**

- The heat: it isn't the job the bulb is for
- The light
- Neither

* Answer: The heat: it isn't the job the bulb is for

<!-- Speaker note: The useful output is what the device is for; by-products are the rest, usually heat and sometimes sound. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Not destroyed

**Is the by-product heat from a bulb destroyed?**

- Yes: by-products are destroyed
- No: it spreads into the room, where it is hard to use
- It turns back into electricity

* Answer: No: it spreads into the room, where it is hard to use

<!-- Speaker note: The heat warms the air a little. It isn't lost, just spread out and not useful. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Two more devices

**For each device, is it the useful output or a by-product?**

Groups: Useful output · By-product

Electric kettle: heat in the water · Electric kettle: heat escaping into the kitchen air · Electric kettle: the rumbling sound · Fan: moving air · Fan: the motor getting warm · Fan: the whirring sound

* Answer: Electric kettle: heat in the water → Useful output; Electric kettle: heat escaping into the kitchen air → By-product; Electric kettle: the rumbling sound → By-product; Fan: moving air → Useful output; Fan: the motor getting warm → By-product; Fan: the whirring sound → By-product

<!-- Speaker note:  -->

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## Elaborate: a speaker

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fscience%2Fphysics-8%2Ftransform%2Fstep-4&code=widget%3A+energy%0Amode%3A+chain%0Astage%3A+Phone+battery+%7C+chemical%0Astage%3A+Circuit+%7C+electrical%0Astage%3A+Speaker+cone+%7C+kinetic+%7C+heat%0Astage%3A+The+air+%7C+sound%0A&fresh=1}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/physics-8/transform/?full=step-4#step-4)

<!-- Speaker note: What this step is for: A four-stage chain with a by-product in the middle checks the rule on an unfamiliar device. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Where the heat comes from

**The speaker cone gets slightly warm. Where in the flow does that heat come from?**

- From the sound
- From the battery directly
- A by-product when electrical energy becomes movement of the cone

* Answer: A by-product when electrical energy becomes movement of the cone

<!-- Speaker note: Each transformation tends to give off a little heat: here, in the speaker's coil and cone. -->

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<span style="background:#fef3c7; color:#1a1a1a; border:1.5px solid #f59e0b; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✍️ Activity</span>

## Elaborate: a bow and arrow

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fscience%2Fphysics-8%2Ftransform%2Fstep-5&code=widget%3A+energy%0Amode%3A+chain%0Astage%3A+Archer%27s+muscles+%7C+chemical+%7C+heat%0Astage%3A+Bent+bow+%7C+elastic%0Astage%3A+Flying+arrow+%7C+kinetic+%7C+sound%0A&fresh=1}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/physics-8/transform/?full=step-5#step-5)

<!-- Speaker note: What this step is for: Elastic potential in a bent bow shows a transformation into stored energy and back out again. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Drawing it back

**Why does a bow need to be drawn back before the arrow can fly?**

- To aim it
- To warm it up
- Drawing it stores elastic potential energy, which becomes the arrow's kinetic energy

* Answer: Drawing it stores elastic potential energy, which becomes the arrow's kinetic energy

<!-- Speaker note: The archer's chemical energy is stored as elastic potential in the bow, then released as the arrow's kinetic energy. -->

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## Evaluate: look back

Write one sentence: "At first I thought… Now I think… because…"

**Revision summary**

- **Transfer**: the same type of energy moves to a new place (heat into your hands, sound to your ear).
- **Transformation**: energy changes type (chemical → electrical → light in a torch).
- Almost every transformation also makes **by-product** heat (and sometimes sound) that isn't the useful output.
- By-product energy isn't destroyed: it spreads into the surroundings.

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Exit ticket

**A wind-up toy runs across the floor. Is 'spring to moving wheels' a transfer or a transformation? Name a by-product.**

* A transformation (elastic potential to kinetic). By-products: heat (friction) and sound.

<!-- Speaker note: Students answer on paper or a mini whiteboard before the reveal. Anyone who cannot answer needs the main idea again next lesson. Where this leads: Next: Follow the energy (nodes 5 and 6), then Year 9 conservation and efficiency. In class: a circus of devices (torch, wind-up toy, buzzer, hand-crank generator) with a flow diagram for each; feel which parts get warm. -->