Conduction, convection, and radiation

Learners aged 12–13 explain conduction, convection and radiation qualitatively using the particle model, organised under one rule: a temperature difference drives energy from hotter to cooler until the difference disappears (thermal equilibrium). The central move is making the learner state explicitly WHAT moves in each case — energy handed along particles that vibrate about fixed positions (conduction), the bulk fluid physically circulating (convection), and an infrared wave that needs no medium and can cross even a vacuum (radiation) — and tying the rate of transfer to the size of the temperature difference. Activities span an interactive particle sandbox, a sorting/assessment check, a reference triptych, a Socratic misconception dialogue, and a spatial loop view, each with a distinct purpose.

• 'Cold flows / cold gets in' — treating cold as a substance that travels. Energy only ever moves from hotter to cooler; a cold object gains energy, it does not emit cold.
• 'Heat rises' — over-generalised. It is warmed FLUID (less dense air/water) that rises in convection; heat itself has no inherent upward direction, and conduction/radiation are not 'up'.
• Confusing temperature with heat / thermal energy — temperature measures average particle kinetic energy; a large warm object can hold more thermal energy than a small hot one.
• 'Metal is colder than wood' — objects in the same room are at the same temperature; metal merely conducts energy away from the hand faster, so it FEELS colder.
• 'Convection is heat moving through the liquid/gas' — in convection the fluid itself physically circulates; the energy is carried by moving matter, not passed through stationary matter.
• 'Radiation means nuclear / is only from very hot or dangerous things' — all objects emit and absorb infrared radiation at all times; it needs no medium and is not inherently harmful.
• 'Wool / a blanket / a coat gives out heat or warms things up' — insulators slow energy transfer; they do not generate heat (a blanket round ice keeps it cold).
• Believing the rate of transfer is constant — it depends on the temperature difference, so a hot object cools quickly at first and ever more slowly as it nears equilibrium.
• Assuming metals are the only conductors / that 'good conductor' and 'gets hot easily' are the same — conduction is about how fast energy passes through, not how hot a thing gets.

• Particle diagram of conduction — a row of fixed, vibrating particles passing energy along to neighbours; free electrons added for metals to show why metals conduct fastest.
• Convection-current loop — a cross-section (beaker or room) with arrows showing warmed fluid expanding, becoming less dense, rising, cooling and sinking; the MATERIAL circulates, the heat does not 'pass through' stationary fluid.
• Infrared radiation arrows across a gap / vacuum — wavy IR emitted and absorbed with no medium; thermal-imaging (false-colour) photos.
• The metal-vs-wood 'same temperature, different feel' demo — separating temperature from rate of conduction and from sensation.
• Leslie cube / surface-colour comparison — matt black vs shiny silver faces emitting/absorbing IR at different rates.
• A temperature-difference → rate dial: bigger difference = faster transfer; the cooling curve that steepens with a larger gap and flattens as equilibrium nears.

• Frame everything under ONE rule first — energy moves from hotter to cooler until the temperature difference disappears (thermal equilibrium) — then present the three mechanisms as three different ways that rule is carried out.
• For EACH mechanism, make the child state explicitly WHAT moves: conduction = energy passed along by particles that stay put; convection = the heated fluid itself physically circulates; radiation = an infrared wave crosses a gap with no particles needed. This single distinction pre-empts most errors.
• Use particle diagrams as the backbone: vibrating, fixed particles handing energy to neighbours (conduction, with free electrons drawn in metals to explain why metals are fast); a convection loop showing warmed fluid expanding, rising, cooling, sinking; radiation as wavy IR arrows across empty space.
• Confront the 'cold flows in' idea head-on with the hotter-to-cooler rule: cold is not a substance that travels; a cold object simply gains energy and the warm one loses it. Use a draught / ice example and ask 'is cold coming in, or is warmth leaving?'
• Use the metal-vs-wood 'feel' demonstration: two objects at the SAME room temperature feel different because metal conducts energy away from your warm hand faster — separating temperature from rate of conduction, and feeling from temperature.
• Teach radiation as universal: ALL objects emit and absorb infrared (not just hot or 'dangerous' things); use thermal-imaging examples and the matt-black-vs-shiny surface result (dark, dull surfaces are better emitters and absorbers).
• Link rate to temperature difference quantitatively-in-words: a bigger temperature difference means a faster transfer, and the rate falls as the difference shrinks — connect to why a hot drink cools fast at first then slowly.
• Sort everyday examples by mechanism and by 'what moves' (radiator warms a room mostly by convection despite its name; the Sun reaches us by radiation through empty space; a metal spoon in soup by conduction) to force application of the model.