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Topic ladders · Physics

Heat

One topic, four rungs: from Classes 1–3 to Classes 11–12. Start at your own stage, or climb from the bottom. Every rung follows the same six steps: Notice, Guess, Try, Observe, Explain, Ask another question.

Print the family table: all four rungs side by side on one sheet, so everyone at home can find their own rung.

Choose your class stage

Rung 1 · Classes 1–3

Hot and Cold

Before you start: safety and help

For the grown-up who helps.

  • Safety: No hot water from the stove or kettle. Warm water should feel comfortable on your own wrist first, like bath water.

What you need

  • A bowl of warm water (tested by a grown-up), a bowl of cold water, room-temperature objects (steel spoon, wooden block, cloth, stone)
  • Safe containers

Child steps

  1. Notice. Some things feel hot, some feel cold.
  2. Guess. Which objects will feel warmer or colder than your hand?
  3. Try. Carefully touch the different objects and dip a finger in each bowl of water.
  4. Observe. Sort them into warmer, cooler, and about the same as your hand.
  5. Explain. Tell someone how you decided.
  6. Ask another question. What makes something heat up or cool down?
For teachers
  • Learning aims: Explore the concepts of hot and cold through safe sensory experience.
  • Key vocabulary: hot, cold, warm, temperature, heat.
  • Note: The steel spoon usually feels colder than the wooden block, though both are at room temperature. Metal takes heat from your hand faster. Older children can check with a thermometer.
  • Review: Children give examples of hot and cold objects.

Rung 2 · Classes 4–7

How Heat Travels

Before you start: safety and help

For the grown-up or teacher who helps. Students: read it too, so you know the rules.

  • Safety: You pour the water and place the spoons. Children watch and do not touch the spoons until the water has cooled. The plastic spoon may soften or bend.

What you need

  • Steel spoon, wooden spoon, plastic spoon (all about the same length)
  • A cup or bowl of warm-to-hot water, poured by a grown-up (from the hot tap or a kettle that has cooled a little; not boiling)
  • Butter or ghee and three small seeds or beads

Student steps

  1. Notice. Heat can move from one place to another.
  2. Guess. Which spoon handle will get warm first when the spoons stand in hot water?
  3. Try. Stick a small blob of butter with a seed pressed into it at the same height on each handle. A grown-up stands the spoons in the water together.
  4. Observe. Which seed drops first? Which material conducted heat best?
  5. Explain. Explain that heat travels better through some materials than others.
  6. Ask another question. Why are cooking pots metal but their handles often plastic or wood?
For teachers
  • Learning aims: Observe conduction of heat; identify good and poor conductors.
  • Key vocabulary: heat, conduction, conductor, insulator.
  • Review: Students name one good and one poor conductor and give a use for each.

Rung 3 · Classes 8–10

Expansion and Change of State with Heat

Before you start: safety and help

For the grown-up or teacher who helps. Students: read it too, so you know the rules.

  • Safety: No flames or stove at home for this activity. Warm tap water is enough to loosen the lid.

What you need

  • A glass jar with a tight metal lid, warm tap water
  • Ice, a cup, a thermometer if available
  • At school only: ball-and-ring apparatus and a burner, used by a teacher

Student steps

  1. Notice. Heating can change the size or state of materials.
  2. Guess. What happens to a metal when heated? What happens to ice?
  3. Try. Close the jar tightly, then hold the lid under warm tap water for a minute and try opening it. Put crushed ice in a cup, stir, and record the temperature every minute while it melts. At school, watch the teacher's ball-and-ring demonstration.
  4. Observe. Record observations carefully. What happens to the temperature while the ice is still melting?
  5. Explain. Link expansion and change of state to heating (the particle model).
  6. Ask another question. How is thermal expansion allowed for in bridges and railway tracks?
For teachers
  • Learning aims: Observe thermal expansion and change of state; relate them to the particle model at an introductory level.
  • Key vocabulary: expansion, contraction, melting, boiling, temperature.
  • Expected results: the lid loosens because the metal expands more than the glass. Stirred melting ice stays close to 0 °C until it has all melted, then the temperature rises: the heat goes into changing the state, not raising the temperature. Bridges have expansion joints and rail tracks have small gaps or are fixed under tension.
  • Review: Students describe one observation and its practical consequence.

Rung 4 · Classes 11–12

Specific Heat Capacity and Heat Transfer

Before you start: safety and help

For the grown-up or teacher who helps. Students: read it too, so you know the rules.

  • Safety: School laboratory with a teacher. Blocks and heaters get hot enough to burn: handle with tongs and let them cool. Never switch on an immersion heater unless it is inside the block or water.

What you need

  • School laboratory only: metal blocks (aluminium, copper, steel) with holes for an immersion heater and thermometer, low-voltage electric immersion heater, power supply with ammeter and voltmeter (or joulemeter), insulation, balance, stopwatch

Student steps

  1. Notice. Different materials require different amounts of heat to raise their temperature.
  2. Guess / Hypothesise. Which material will show a larger temperature change for the same heat input?
  3. Try. Perform an experiment to determine specific heat capacity (energy supplied = voltage × current × time) or to compare heat transfer.
  4. Observe. Record masses, temperatures and times carefully.
  5. Explain. Calculate specific heat capacity using E = mcΔT and discuss sources of error (heat loss, etc.).
  6. Ask another question. How is knowledge of specific heat used in engineering or climate science?
For teachers
  • Learning aims: Determine specific heat capacity experimentally; analyse energy transfer and experimental error.
  • Reference values: water about 4,200 J/kg °C, aluminium about 900, copper about 390. Measured values are usually too high, because heat escapes to the room.
  • Review: Students present results, calculation and evaluation.

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