The shape of the lesson
By the end of the lesson, learners can
- Send heat down the bar: Heat one end of a material and watch energy travel along it from the hot end to the cold end.
- Why metals win: Conduction depends on how readily particles can pass energy on, which is why materials differ so much.
- Lattice vibrations: heated particles vibrate more and pass energy to neighbours (all solids, slow).
- Free electrons: in metals these move quickly and carry energy fast (so metals are the best conductors).
- Insulators: non-metals, liquids and gases conduct poorly.
One picture every idea returns to
Conduction is the transfer of thermal energy through a material without the material itself moving. Vibrating particles pass energy to their neighbours; metals conduct best because they also have free electrons that carry energy quickly.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Passed along, particle to particle.. Leave a metal spoon in a hot drink and the handle is soon too warm to hold, yet a wooden spoon stays cool. | Whole class, then pairs |
| 5 to 17 min | Teach and check: Send heat down the bar | Heat one end of a material and watch energy travel along it from the hot end to the cold end. Project tab 4 of the lab (Conduction) and let a student drive it while the class predicts. | Whole class, then pairs |
| 17 to 30 min | Teach and check: Why metals win | Conduction depends on how readily particles can pass energy on, which is why materials differ so much. | Mix-Pair-Share |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 13 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Why metals win, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Mix-Pair-Share
Students mix around the room until you call pair; they pair with the nearest classmate, discuss the prompt, then mix again. Three prompts of rising difficulty, three different partners.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| In conduction the material itself does not flow. | The particles stay roughly where they are and simply pass energy to their neighbours by vibrating harder, so only the energy travels along the material. |
Conduction: worksheet
6 questions, 13 marks. Written in the style of the papers; no past paper question is reproduced.
Define thermal conduction.
Explain how energy is conducted through a solid that is not a metal, such as glass.
Explain why metals are much better thermal conductors than non-metals.
Explain why gases are very poor conductors of thermal energy.
A student says that during conduction the hot part of a metal bar moves along to the cold end. Explain why this is wrong.
A metal saucepan is given a plastic handle. Explain why plastic is a sensible choice for the handle.
Answer key and marking notes
- Conduction is the transfer of thermal energy through a material. ✓
- It happens without the material itself moving from one place to another. ✓
- Particles at the hot end gain energy and vibrate more strongly. ✓
- They collide with neighbouring particles, passing energy along the material. ✓
- Metals contain free (delocalised) electrons that can move through the material. ✓
- At the hot end these electrons gain energy and move quickly to the cooler end. ✓
- They carry energy far faster than vibrations alone, so metals conduct much faster. ✓
- The particles in a gas are far apart, so they collide much less often. ✓
- Energy is passed on only rarely, and there are no free electrons, so conduction is very slow. ✓
- The material (the particles of the bar) does not travel along; the particles stay in place and vibrate. ✓
- Only energy is transferred along the bar, passed from particle to particle (and by free electrons). ✓
- Plastic is a poor conductor (a good insulator), with no free electrons. ✓
- So little energy is conducted to the handle, keeping it cool enough to hold safely. ✓
3 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
Why are metals good conductors of thermal energy?
- AThey contain free (delocalised) electrons that carry energy quickly through the metal.
- BThey have unusually heavy atoms.
- CThey have shiny surfaces.
- DThey contain trapped pockets of air.
A metal spoon and a wooden spoon are left standing in a pan of hot soup. Why does the metal spoon feel hot to the touch sooner?
- AMetal conducts thermal energy to your hand faster than wood does.
- BThe metal spoon is heavier.
- CWood stores more energy than metal.
- DThe wooden spoon reflects the heat.
Heat is applied to one end of a solid metal rod. By which process is thermal energy mainly transferred along the rod?
- Aconduction
- Bconvection
- Cradiation
- Devaporation
Quiz key
Free electrons move quickly through a metal, carrying kinetic energy from the hot end to the cold end, on top of the slower lattice-vibration transfer. Non-metals lack these free electrons, so they conduct poorly.
Metal is a far better thermal conductor, so energy travels up the handle to your hand quickly; wood is an insulator and conducts slowly. Mass and reflection are not the reason.
In a solid the particles cannot move through the material, so energy passes along by conduction (vibrations and free electrons). Convection needs a moving fluid, which a solid is not.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.