Series & Parallel Calculations

Lesson 4 of 4: Calculating Values in Series and Parallel Circuits

Duration: 50 minutes
Class size: 30 Year 10 students
Unit: Circuit Connections Unveiled
National Curriculum Link:

• KS4 Physics - Electricity: “Apply the concept of potential difference, current, resistance and power in circuits” (Programme of Study for Science, Physics, National Curriculum 2014)
• Specifically: “Use and apply formulae including Ohm’s law (V=IR) to calculate voltage, current or resistance.” (Physics, Year 10)
• Also references “Analyse series and parallel circuits in terms of total resistance, current and voltage.”

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Learning Objectives (WALT)

• WALT calculate total resistance, current and voltage in series and parallel circuits using Ohm’s Law
• WALT apply problem-solving skills to predict behaviour of complex circuits
• WALT interpret circuit diagrams accurately to perform calculations

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Success Criteria

• I can correctly calculate total resistance in series and parallel circuits
• I can use Ohm’s Law to find voltage drops and current through individual components
• I can explain differences in current and voltage between series and parallel components
• I can solve worded problems involving combined series-parallel circuits

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Resources

• Whiteboard and markers
• Circuit diagrams worksheets (dyslexia-friendly format: clear font - Comic Sans or Arial, ample spacing, colour-coded components)
• Calculators
• PowerPoint slides with worked examples and animations
• Mini-whiteboards for student responses
• Extension problem-solving task sheets
• Timer countdown app on board to manage activities

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Lesson Structure

1. Starter Activity (5 mins)

• Review quick quiz on key concepts from previous lessons: definitions of current, voltage, resistance, + Ohm’s Law formula.
• Use mini-whiteboards: e.g. Write down formula for Ohm’s Law and how resistors add in series/parallel (total resistance equations).
• Teacher checks understanding instantly, addresses common errors.

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2. Direct Teaching (10 mins)

• Explain and demonstrate:
  • Recap formulas:
    • Series resistance: ( R_{total} = R_1 + R_2 + \dots )
    • Parallel resistance: ( \frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + \dots )
  • Voltage in series adds up, current is the same; voltage splits in parallel, current adds up.
  • Use visual animations on screen showing electrons and voltage/current flow in each circuit type.
  • Solve one worked example of each circuit type calculating total resistance, voltage drops and currents.
  • Emphasise units and working methodically for clarity – caters to dyslexic students by modelling stepwise approach with colour coding.

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3. Guided Practice (15 mins)

• Students work in pairs with differentiated worksheets:
  • Support group: simpler circuits, fill-in-the-blank style with partially completed calculations, scaffolded hints provided.
  • Most students: normal problem sets with completed calculations required, mixture of series and parallel circuits.
  • Advanced learners: more complex combined circuits (series-parallel) and word problems involving power calculations as extension.
• Teacher circulates and supports – modelling and questioning focusing on reasoning behind each step, e.g. “Why does current stay the same in series?”
• Dyslexia-friendly reading options: use coloured highlighted keywords, simplified sentence structures, and icons for resistance, current, voltage.

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4. Independent Application (15 mins)

• Individual task: Solve 2-3 complex circuit calculations (combining series and parallel components). Write full calculation steps and final answers.
• Use mini-whiteboards to self-assess and peer-assess answers in pairs after completion, encouraging confidence and collaborative learning.
• Extension task on worksheet for early finishers or advanced learners: calculate power dissipation of components using ( P = IV ).

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5. Plenary & Assessment (5 mins)

• Quick “exit ticket”: Each student writes down one example of how voltage or current behaves differently in series vs parallel.
• Share 3-4 examples with class, teacher clarifies any misconceptions.
• Reflect on success criteria: which have you achieved? Which do you need to practise more?

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Differentiation Strategies

• Visual learners: Animations and colour-coded steps during explanations
• Support learners & students with dyslexia: Simplified text, larger font, glossaries, stepwise instructions, paired work, reading aloud questions
• Advanced learners: Extension problems and opportunities to explain reasoning orally or in writing
• Kinesthetic learners: Use mini-whiteboards for active responding and partner explanations

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Assessment

• Formative assessment through mini-whiteboards and guided practice feedback
• Summative assessment in independent worksheet task, marked with reference to success criteria
• Peer and self-assessment during plenary for deeper processing

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Notes for Teachers

• Reinforce correct use of units (ohms, volts, amps) consistently to build good practice for exams.
• Encourage students to verbalise their thought processes to deepen understanding.
• Provide scaffolded templates for calculations to reduce cognitive load for students who struggle with sequencing steps.
• Highlight real-world applications: How understanding these calculations is important in household wiring and device safety.

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Thank you for teaching the final lesson of this exciting unit!

Your thoughtful incorporation of varied learning styles and careful linking to the National Curriculum will ensure your students leave with a robust understanding of circuits and essential science skills.