Science KS4 Y10Y11 Exemplar

Resistance and Wire Length

4 lessons

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Subject
Science
Key Stage
KS4
Year group
Y10, Y11
Statutory reference
GCSE Physics: resistance as the opposition to current; V = IR
Source document
Physics (KS4) - National Curriculum Programme of Study
Estimated duration
4 lessons
Status
Exemplar
Coverage: 9/13 expected capabilities surfaced
Curriculum anchorConcept modelDifferentiation dataThinking lensLesson structureSubject referencesVocabulary definitionsPrior knowledge linksLearner scaffolding
Cross-curricular linksSuccess criteriaAssessment alignmentAccess and inclusion

Enquiry questions

  • What is the relationship between the length of a wire and its resistance?

    • Concepts

    This study delivers 1 primary concept and 4 secondary concepts.

    Primary concept: Current, Potential Difference and Resistance (PH-KS4-C003)

    Type: Knowledge | Teaching weight: 3/6

    Electric current (I) is the rate of flow of electric charge: I = Q/t. Potential difference (V) is the work done per unit charge: V = W/Q. Resistance (R) is the ratio of potential difference to current: R = V/I (Ohm's law). For an ohmic conductor at constant temperature, resistance is constant. Resistance of a filament bulb increases with temperature; a thermistor's resistance decreases with temperature; a diode allows current in one direction only.

    Teaching guidance: Required Practicals 15 and 16: investigate series and parallel circuits, and plot I-V characteristics. Pupils need extensive practice with circuit calculations — use structured problem-solving with V = IR as the starting point. Connect resistance to the microscopic model: electrons colliding with lattice ions. Explain the thermistor in terms of more charge carriers at higher temperatures. Use the diode I-V characteristic to explain rectification of AC. Key vocabulary: current, potential difference, voltage, resistance, Ohm's law, ohmic conductor, I-V characteristic, series circuit, parallel circuit, thermistor, diode, LDR, ammeter, voltmeter Common misconceptions: Students confuse current and potential difference: current is the flow of charge; potential difference is the energy per unit charge driving the flow. Students also think current is 'used up' in components — in a series circuit, the same current flows throughout. Students draw ammeters in parallel and voltmeters in series, reversing the correct connections.

    Differentiation

    LevelWhat success looks likeExample taskCommon errors

    EmergingIdentifies current as the flow of charge, potential difference as the push on charges, and resistance as opposition to flow. Draws and recognises simple series and parallel circuits.Draw a series circuit with a battery, ammeter, lamp, and voltmeter measuring the potential difference across the lamp. Label each component.Drawing the voltmeter in series with the lamp rather than in parallel across it; Confusing the circuit symbols for ammeter (A in circle) and voltmeter (V in circle)
    DevelopingApplies V = IR to calculate current, p.d., or resistance. Describes how current and p.d. behave in series and parallel circuits. Interprets I-V characteristic graphs for resistors, filament lamps, and diodes.A 6 V battery is connected to two resistors in series: 4 Ω and 8 Ω. Calculate the current and the potential difference across each resistor.Using individual resistance instead of total resistance to calculate the current from the supply; Forgetting that in a series circuit, the p.d.s across components must sum to the supply p.d.
    SecureAnalyses combined series-parallel circuits, explains non-ohmic behaviour using particle models (filament lamp, thermistor, LDR, diode), and applies the charge equation Q = It alongside V = IR.A thermistor is connected in series with a 100 Ω fixed resistor and a 6 V supply. At 20°C the thermistor has resistance 400 Ω; at 50°C it drops to 100 Ω. Calculate the p.d. across the fixed resistor at each temperature and explain the application.Confusing the p.d. across the thermistor with the p.d. across the fixed resistor; Not explaining that the thermistor's resistance decreases with temperature due to more charge carriers being released
    MasteryDesigns and evaluates circuits for specific purposes, analyses experimental I-V data critically, and explains the physics underlying component behaviour at a particle level, including energy transfers within circuits.A student claims that a filament lamp obeys Ohm's law because 'when you increase the voltage, the current increases.' Evaluate this claim using I-V characteristic data and particle theory.Failing to distinguish between 'current increases with voltage' and 'current is directly proportional to voltage'; Not linking the curvature of the I-V graph to the physical mechanism of increased lattice vibrations at higher temperatures

    Model response (Emerging): The circuit shows a battery connected in a single loop with an ammeter in series and a lamp. A voltmeter is connected in parallel across the lamp. The ammeter is drawn in the main loop; the voltmeter branches off and reconnects around the lamp.
    Model response (Developing): Total resistance = 4 + 8 = 12 Ω. Current = V/R = 6/12 = 0.5 A. P.d. across 4 Ω = IR = 0.5 × 4 = 2 V. P.d. across 8 Ω = IR = 0.5 × 8 = 4 V. Check: 2 + 4 = 6 V (equals supply p.d.).
    Model response (Secure): At 20°C: total R = 400 + 100 = 500 Ω, I = 6/500 = 0.012 A, p.d. across fixed resistor = 0.012 × 100 = 1.2 V. At 50°C: total R = 100 + 100 = 200 Ω, I = 6/200 = 0.03 A, p.d. across fixed resistor = 0.03 × 100 = 3.0 V. As temperature rises, the p.d. across the fixed resistor increases. This potential divider arrangement can trigger a switch (e.g. a fire alarm) when voltage exceeds a threshold.
    Model response (Mastery): The claim is incorrect. While current does increase with voltage, Ohm's law requires a linear (directly proportional) relationship — constant resistance. A filament lamp's I-V graph is curved: at higher voltages, the filament heats up, metal ions vibrate more, and conduction electrons collide more frequently with the lattice, increasing resistance. The graph shows a decreasing gradient (I increases more slowly than V). This means the lamp is non-ohmic. The student has confused 'current increases with voltage' (true for most components) with 'current is directly proportional to voltage' (only true for ohmic conductors at constant temperature).

    Secondary concept: Energy Stores and Transfers (PH-KS4-C001)

    Type: Knowledge | Teaching weight: 3/6

    Energy is stored in physical systems in various ways: kinetic (moving objects), gravitational potential (objects above a reference level), elastic potential (deformed objects), chemical (fuels, food), thermal (hot objects), nuclear (unstable nuclei), electromagnetic (electric/magnetic fields). Energy is neither created nor destroyed (conservation of energy) but transferred between stores by mechanical work, electrical work, heating or radiation. Useful energy transfers are always accompanied by dissipation to the thermal store of the surroundings.

    Differentiation

    LevelWhat success looks likeCommon errors

    EmergingIdentifies basic energy stores (kinetic, thermal, gravitational potential) and recognises that energy can be transferred between stores.Describing energy as being 'used up' or 'created' rather than transferred between stores; Confusing energy stores with energy transfer pathways (e.g. saying 'sound energy store')
    DevelopingDescribes energy transfers using correct store terminology, calculates kinetic and gravitational potential energy using standard formulae, and recognises conservation of energy.Forgetting to state the assumption about negligible air resistance when equating GPE to KE; Using incorrect units or confusing mass in kg with weight in N in the GPE formula
    SecureApplies energy conservation quantitatively across multi-step problems, calculates efficiency, and draws and interprets Sankey diagrams for real systems.Drawing Sankey diagram arrows that do not conserve total width (input width must equal sum of output widths); Confusing power (rate of energy transfer) with total energy transferred when calculating efficiency
    MasteryEvaluates energy transfer scenarios critically, combines power, work done, and efficiency in extended calculations, and analyses the limitations of energy models in real-world contexts.Failing to identify multiple dissipation pathways and only listing one source of energy loss; Not linking the impossibility of 100% recovery to fundamental thermodynamic principles

    Secondary concept: Specific Heat Capacity and Latent Heat (PH-KS4-C002)

    Type: Knowledge | Teaching weight: 3/6

    Specific heat capacity (c) is the energy required to raise the temperature of 1 kg of a material by 1°C: Q = mcΔT. Different materials require different amounts of energy for the same temperature change, which explains why water is used as a coolant and why land heats up faster than sea. Latent heat is the energy transferred during a change of state at constant temperature; specific latent heat (L) is the energy required per kilogram: Q = mL.

    Differentiation

    LevelWhat success looks likeCommon errors

    EmergingRecognises that different materials heat up at different rates and that changes of state require energy input or release without a temperature change.Stating the metal 'has more heat' rather than explaining the rate of thermal energy transfer; Confusing temperature with thermal energy — believing a small hot object has more energy than a large warm one
    DevelopingUses the specific heat capacity equation (E = mcΔθ) to calculate energy changes for heating and cooling, and identifies specific latent heat as the energy for a change of state.Using the final temperature instead of the temperature change (Δθ) in the equation; Forgetting that during a change of state the temperature remains constant, so SHC equation does not apply
    SecureCombines SHC and specific latent heat calculations in multi-step problems, interprets heating curves showing plateaus at changes of state, and explains the particle model basis for these energy changes.Not recognising that the gradient differs between solid, liquid, and gas phases because they have different SHC values; Confusing latent heat of fusion with latent heat of vaporisation or using the wrong value in calculations
    MasteryEvaluates experimental methods for determining SHC and latent heat, analyses sources of systematic error, and applies combined calculations to unfamiliar engineering or environmental contexts.Stating the experimental value is 'wrong' without identifying the direction and cause of systematic error; Not recognising that energy losses always make the experimental SHC appear lower than the true value

    Secondary concept: Electrical Power and Mains Electricity (PH-KS4-C004)

    Type: Knowledge | Teaching weight: 3/6

    Electrical power is the rate at which energy is transferred: P = IV = I²R = V²/R. Energy transferred is calculated using E = Pt. Mains electricity in the UK is supplied as alternating current at 230 V and 50 Hz. The three-pin plug contains a live wire (brown), neutral wire (blue) and earth wire (green-yellow). The fuse protects the appliance by melting if the current becomes too large; the earth wire provides safety in case of a fault.

    Differentiation

    LevelWhat success looks likeCommon errors

    EmergingRecognises that electrical appliances transfer energy, knows the difference between a.c. and d.c., and identifies basic electrical safety features (fuses, earth wires, insulation).Stating that a.c. is 'stronger' than d.c. rather than describing the directional difference; Not knowing the UK mains supply values (230 V, 50 Hz)
    DevelopingCalculates electrical power using P = IV and P = I²R, determines energy transferred using E = Pt, and explains how fuses and circuit breakers protect circuits from overheating.Selecting a fuse with exactly the same rating as the operating current rather than the next size up; Using the wrong power equation and mixing up variables
    SecureApplies the National Grid model to explain efficient power transmission, uses P = IV and P = I²R to explain why high voltage reduces energy losses, and calculates energy costs using the kilowatt-hour.Stating 'high voltage means less energy lost' without explaining the mechanism via reduced current and I²R; Confusing the transmitted power with the wasted power in the cables
    MasteryEvaluates the efficiency and safety trade-offs in real electrical systems, analyses energy cost scenarios with multiple appliances, and critically discusses the advantages and limitations of different generation and distribution methods.Not understanding that COP > 1 is possible because a heat pump moves existing thermal energy rather than creating it; Failing to evaluate real-world limitations such as seasonal COP variation and installation costs

    Secondary concept: Particle Model, Density and Gas Laws (PH-KS4-C005)

    Type: Knowledge | Teaching weight: 3/6

    The particle model describes matter as composed of tiny particles in constant motion. In solids, particles vibrate about fixed positions; in liquids, particles can flow but remain in contact; in gases, particles move rapidly and are widely separated. Density (ρ = m/V) depends on particle mass and separation. Gas pressure is caused by particles colliding with the container walls. Increasing temperature increases the kinetic energy and speed of particles, increasing the rate and force of collisions.

    Differentiation

    LevelWhat success looks likeCommon errors

    EmergingDescribes the particle arrangements in solids, liquids, and gases, and relates these to macroscopic properties such as shape, volume, and compressibility.Drawing gas particles as stationary or evenly spaced rather than randomly distributed and moving; Stating that particles 'expand' when heated rather than that they move faster and spread further apart
    DevelopingCalculates density using ρ = m/V, describes how temperature relates to average kinetic energy of particles, and explains pressure in gases using particle collisions with container walls.Failing to convert cm³ to m³ correctly (1 m³ = 1,000,000 cm³, not 100 cm³); Mixing grams and kilograms without converting, giving an answer out by a factor of 1000
    SecureApplies the gas laws (pV = constant at constant T; p/T = constant at constant V) to solve problems, links gas pressure to particle kinetic energy and collision frequency, and explains density differences between states using the particle model.Stating that particles 'move faster' when compressed at constant temperature — speed is unchanged, only collision frequency increases; Applying Boyle's law to situations where temperature changes, invalidating the constant-temperature assumption
    MasteryEvaluates the limitations of the simple particle model, applies gas law calculations to unfamiliar contexts, and analyses experimental methods for measuring density of regular and irregular objects including sources of error.Not identifying that trapped air bubbles systematically increase volume and therefore decrease the density calculation; Confusing systematic errors (air bubbles, porous stone) with random errors (reading the meniscus) in evaluation

    Thinking lens: Patterns (primary)

    Key question: What patterns can I notice here, and what do they allow me to predict? Why this lens fits: Data from repeated investigations reveals patterns that allow pupils to generalise their findings beyond the specific test conditions. Question stems for KS4:
  • How would you formalise this pattern mathematically?
  • What are the limits of this pattern — where does it break down?
  • Could this pattern be an artefact of how the data was collected?
  • Does identifying the pattern tell us why it occurs?
    • Secondary lens: Cause and Effect — Fair testing and investigations are designed to isolate variables and establish causal relationships — the cognitive demand is reasoning from controlled evidence to causal claims.

    Session structure: Fair Test

    Fair Test

    The classic scientific enquiry: formulating a testable question, making a prediction based on scientific understanding, designing a method that controls variables, collecting and recording data systematically, analysing results, and drawing a conclusion linked back to the original hypothesis.

    question → hypothesis → method → data_collection → analysis → conclusion Assessment: Structured scientific report including question, hypothesis with reasoning, method with variables identified, results table/graph, and conclusion evaluating whether results support the hypothesis. Teacher note: Use the FAIR TEST template: expect pupils to derive a testable hypothesis from scientific theory and design a rigorous method with appropriate controls, precision, and sample size. Guide analysis using statistical techniques or mathematical modelling where appropriate. Demand critical evaluation of validity, reliability, accuracy, and the extent to which results support or refute the hypothesis. KS4 question stems:
  • How does your hypothesis follow from the underlying scientific theory?
  • How have you ensured sufficient precision, accuracy, and reliability in your method?
  • What statistical analysis supports your conclusion?
  • To what extent do your results support the hypothesis, and what are the limitations?

    • Variables

    Independent: length of constantan wire (20cm, 40cm, 60cm, 80cm, 100cm) Dependent: resistance (calculated from V/I) Controlled: wire material and thickness (SWG), temperature (keep current low), same power supply voltage

    Equipment and safety

    Equipment:
  • constantan wire (SWG 28 or 30)
  • metre ruler
  • ammeter
  • voltmeter
  • power supply (variable DC, max 3V)
  • connecting wires with crocodile clips
  • switch
  • safety goggles
    • Safety notes: Keep the current low and duration short to prevent the wire overheating — switch off between readings. The wire can get hot enough to burn at high currents. Do not exceed 3V. Ensure the wire is firmly secured to the ruler. Use safety goggles in case the wire snaps under tension. (Hazard level: low)

    Expected outcome

    Resistance is directly proportional to wire length: doubling the length doubles the resistance. A graph of resistance vs length passes through the origin and is a straight line. This is because a longer wire provides more resistance to electron flow — electrons must travel further through the lattice of metal ions and collide with more ions. R = V/I is used to calculate resistance at each length.

    Recording format: data table of length, voltage, current, and calculated resistance, graph of resistance vs length, gradient calculation, conclusion stating proportional relationship

    Enquiry type

    Fair Test

    A controlled investigation where one variable is deliberately changed while all others are kept the same, to determine whether the changed variable has an effect on a measured outcome. The gold-standard enquiry type for causal questions in science.

    Question stems:
  • How does [independent variable] affect [dependent variable]?
  • Does changing [variable] make a difference to [outcome]?
  • What is the relationship between [variable A] and [variable B]?
    • Teacher scaffold:
  • What will you change? (independent variable)
  • What will you measure or observe? (dependent variable)
  • What will you keep the same? (controlled variables)
  • What do you predict will happen? Why?
  • Was your prediction correct? What does the evidence show?

    • Known misconceptions

    Electricity is used up

    What pupils may say: Electricity is used up by the bulb — it gets used up as it goes around the circuit. Correct explanation: Electric current flows around a complete circuit and is the same at all points in a series circuit. The bulb transfers electrical energy to light and thermal energy, but the current itself is not consumed. What is transferred is energy, not electricity. An ammeter would show the same reading before and after the bulb. Diagnostic questions:
  • If you put an ammeter before the bulb and one after the bulb in a series circuit, what would you expect to see?
  • What happens to the electricity after it goes through the bulb?
  • Is it electricity or energy that is 'used up'?

    • Why this study matters

    This required practical produces one of the cleanest proportional relationships in GCSE science — resistance vs length is reliably linear through the origin. This makes it ideal for teaching graph skills: plotting, drawing a line of best fit, calculating a gradient, and identifying proportionality. The practical also reinforces V = IR as a working tool for calculation rather than an abstract equation, and the physical model (electrons colliding with ions in a longer lattice) provides a concrete explanation.

    Pitfalls to avoid

  • Pupils leave the circuit on too long, causing the wire to heat up — temperature increase changes resistance and confounds results; keep measurements brief
  • Connecting the ammeter in parallel or the voltmeter in series — revise circuit component placement before starting
  • Plotting V or I against length rather than calculating R first — pupils must process their data before plotting

    • Vocabulary word mat

    TermMeaning

    absolute temperature
    alternating current
    ammeter
    boiling
    boyle's law
    change of state
    charles' law
    chemical energy
    circuit breaker
    combined gas law
    condensation
    conservation of energy
    current
    density
    diode
    direct current
    dissipation
    double insulation
    earth wire
    elastic potential energy
    electrical power
    electromagnetic energy
    energy store
    energy transfer
    evaporation
    frequencyHow many times something vibrates each second. The higher the frequency, the higher the pitch of the sound.
    fuse
    gravitational potential energy
    i-v characteristic
    internal energy
    joulemeter
    kelvin
    kilowatt-hour
    kinetic energy
    latent heat
    ldr
    live wire
    melting
    neutral wire
    nuclear energy
    ohm's law
    ohmic conductor
    parallel circuit
    particle model
    peak voltage
    potential difference
    pressure
    random motion
    resistance
    sankey diagram
    series circuit
    specific heat capacity
    specific latent heat
    temperature
    thermal energy
    thermistor
    voltage
    voltmeter
    ohm
    directly proportional
    electron flow
    lattice

    Prior knowledge (retrieval plan)

    Pupils should already know the following from earlier units:

    Prior knowledge neededFor conceptDescription

    Particle model of matterParticle Model, Density and Gas LawsUnderstanding that matter is made of particles with properties explained by their arrangement and...
    States of matterParticle Model, Density and Gas LawsUnderstanding the properties of solid, liquid, and gas states in terms of particles
    Gas pressureParticle Model, Density and Gas LawsUnderstanding gas pressure in terms of particle collisions
    Thermal equilibriumSpecific Heat Capacity and Latent HeatUnderstanding heat transfer from hot to cold objects and the role of insulators
    Energy transfer processesEnergy Stores and TransfersKnowledge of processes that involve energy transfer (motion, gravity, electricity, springs, metab...
    Energy conservationSpecific Heat Capacity and Latent HeatUnderstanding that total energy is conserved in any change
    Energy in systemsEnergy Stores and TransfersAbility to describe energy changes in systems over time
    Electric currentElectrical Power and Mains ElectricityUnderstanding electric current as flow of charge measured in amperes
    Circuit typesCurrent, Potential Difference and ResistanceKnowledge of series and parallel circuits and current behavior
    Potential differenceCurrent, Potential Difference and ResistanceUnderstanding potential difference measured in volts
    ResistanceCurrent, Potential Difference and ResistanceUnderstanding resistance as the ratio of voltage to current
    States propertiesParticle Model, Density and Gas LawsKnowledge of similarities and differences between solid, liquid, and gas states including density
    Particle arrangementsParticle Model, Density and Gas LawsUnderstanding how particle arrangements and motion explain properties of states
    Temperature and particlesSpecific Heat Capacity and Latent HeatUnderstanding how temperature affects particle motion and spacing

    Scaffolding and inclusion (Y10)

    GuidelineDetail

    Reading levelGCSE Year 1 Reader (Lexile 1000–1300)
    Text-to-speechAvailable
    VocabularyFull GCSE specialist vocabulary across all subjects. Exam-board-specific terminology expected. Command words must be used precisely and consistently. Subject-specific registers (scientific, literary-critical, historical, geographical) fully established.
    Scaffolding levelMinimal
    Hint tiers3 tiers
    Session length35–55 minutes
    Feedback toneExamination Coach
    Normalize struggleYes
    Example correct feedbackFull marks. You addressed all assessment objectives: identification (AO1), textual evidence (AO2), and analytical commentary on effect (AO3). Your use of subject terminology was precise.
    Example error feedbackThis response earns 3 of 8 marks. You identified the key feature (AO1 ✓) and quoted correctly (AO2 ✓), but your analysis describes what happens rather than explaining the effect on the reader (AO3 ✗). Additionally, you have not linked to the wider context (AO4 ✗). Revise to include both.

    Knowledge organiser

    Key terms:
  • resistance
  • current
  • potential difference
  • ohm
  • ammeter
  • voltmeter
  • ohmic conductor
  • directly proportional
  • electron flow
  • lattice
    • Core facts (expected standard):
  • Current, Potential Difference and Resistance: Analyses combined series-parallel circuits, explains non-ohmic behaviour using particle models (filament lamp, thermistor, LDR, diode), and applies the charge equation Q = It alongside V = IR.

    • Graph context

    Node type: ScienceEnquiry | Study ID: SE-KS4-014 Concept IDs:
  • PH-KS4-C003: Current, Potential Difference and Resistance (primary)
  • PH-KS4-C001: Energy Stores and Transfers
  • PH-KS4-C002: Specific Heat Capacity and Latent Heat
  • PH-KS4-C004: Electrical Power and Mains Electricity
  • PH-KS4-C005: Particle Model, Density and Gas Laws
    • Cypher query:

    ``cypher

    MATCH (ts:ScienceEnquiry {enquiry_id: 'SE-KS4-014'})

    -[:DELIVERS_VIA]->(c:Concept)

    -[:HAS_DIFFICULTY_LEVEL]->(dl)

    RETURN c.name, dl.label, dl.description

    ``

    Generated from the UK Curriculum Knowledge Graph — zero LLM generation.