MYP6 Unit 2 - Electric networks
Content
Scheme of Work
Electric networks
In this unit students learn how simple electric circuits are constructed, represented and explained. They begin by making a bulb light using simple equipment, then move towards the scientific language of current, voltage and resistance.
Students will use circuit symbols, build series and parallel circuits, measure current with an ammeter, explore conductors and insulators, and investigate how the length of a wire affects resistance.
The unit also includes opportunities for Criterion C experimental work and Criterion D research into scientists connected with electricity and magnetism.
Students will learn
- Symbols used to draw circuit diagrams.
- Current as the flow of electric charge, measured in amperes.
- Voltage as the push and pull provided by a cell or battery, measured in volts.
- Resistance as a measure of how difficult it is for charge to flow through a material, measured in ohms.
- The difference between conductors and insulators.
- The difference between series and parallel circuits.
Students will be able to
- Describe current as a flow of charge.
- Describe voltage as the amount of positive and negative charge maintained at the ends of a battery.
- Describe resistance as a material's opposition to the flow of electric current.
- Use the terms conductor and insulator correctly.
- Construct simple circuits safely and draw them using circuit symbols.
6u2.1 - Introduction to circuits
Students begin by exploring the equipment needed to make a light bulb shine. The purpose of the lesson is to introduce the idea that a working circuit must form a complete loop.
Students should first draw what they actually build before being introduced to formal circuit diagrams.
Activity - Make the bulb shine
Apparatus
- Cells or battery packs.
- Small bulbs or lamps.
- Connecting wires.
- Bulb holders if available.
Task
- Use the fewest possible pieces of equipment to make the bulb light.
- Draw the circuit exactly as it appears on the bench.
- Identify the cell, wires and bulb in the drawing.
- Explain why the circuit stops working if one wire is removed.
Summary
- A circuit must be complete for current to flow.
- A cell provides the energy needed to make charges move around the circuit.
- A bulb lights when current passes through it.
Check your understanding
- What pieces of equipment are needed to make a bulb shine?
- Why does the bulb go out when the circuit is broken?
- What is the difference between drawing the real circuit and drawing a circuit diagram?
Teacher notes & learning objectives
- LO1 - Construct a simple complete circuit.
- LO2 - Recognise that current requires a complete loop.
- LO3 - Begin moving from physical drawings to circuit diagrams.
This is a discovery lesson. Avoid giving the complete solution too early; allow students to test incomplete arrangements and identify why they do not work.
6u2.2 - Circuit symbols and circuit diagrams
Scientific circuit diagrams are simplified drawings that use standard symbols. They allow circuits to be communicated clearly without drawing every physical detail of the equipment.
Students practise building simple circuits and matching them to circuit diagrams.
Circuit symbols
- A wire is shown as a straight line.
- A cell is shown using one long line and one short line.
- A bulb or lamp is shown using a circle with a cross inside.
- A switch can be shown open or closed.
Activity - Circuit exploration
Students construct a set of simple circuits and draw the matching circuit diagrams.
Suggested tasks
- Build circuits with one bulb and one cell.
- Build circuits with more than one bulb.
- Build circuits with more than one cell.
- Compare the brightness of bulbs in the different circuits.
- Draw the circuit diagram for each circuit constructed.
Comparing circuits
If more bulbs are added to a simple series circuit, the bulbs are usually dimmer.
If more cells are added in the same direction, the bulbs are usually brighter.
These observations help introduce the later ideas of voltage and resistance.
Summary
- Circuit diagrams use standard symbols.
- Circuit diagrams show how components are connected, not where they are placed on the bench.
- Changing the number of bulbs or cells changes the behaviour of the circuit.
Check your understanding
- Why do scientists use circuit symbols?
- Draw the symbol for a cell.
- What happens to bulb brightness when more bulbs are added in series?
Teacher notes & learning objectives
- LO1 - Use simple circuit symbols correctly.
- LO2 - Convert a real circuit into a circuit diagram.
- LO3 - Compare circuits containing different numbers of bulbs and cells.
Allow time for a whole-class debrief on circuits containing more bulbs and more cells. These observations provide useful preparation for voltage and resistance.
6u2.3 - Current and ammeters
Electric current is the flow of electric charge. In metal wires, the moving charges are electrons. Current is measured in amperes, often shortened to amps, using an ammeter.
Students reconstruct previous circuits and add an ammeter to measure the current.
Current
Current tells us how much electric charge flows through a part of the circuit each second.
The unit of current is the ampere, symbol A.
An ammeter must be connected in series so that the current flows through the meter.
Activity - Measuring current
Apparatus
- Cells or battery packs.
- Bulbs or lamps.
- Connecting wires.
- Ammeter or multimeter set to current.
Procedure
- Rebuild selected circuits from the earlier circuit exploration.
- Add an ammeter in series.
- Record the current in amperes.
- Compare the current in circuits with different numbers of bulbs and cells.
Summary
- Current is the flow of electric charge.
- Current is measured in amperes.
- An ammeter is connected in series with the component being tested.
Check your understanding
- What is electric current?
- What unit is used for current?
- Why must an ammeter be placed in series?
Teacher notes & learning objectives
- LO1 - Describe current as a flow of charge.
- LO2 - Measure current safely using an ammeter.
- LO3 - Link current readings to circuit observations.
Suggested reading: Electricity and Magnetism, pp. 44-46, covering current, amperes and circuits.
6u2.4 - Conductors and insulators
Conductors allow electric current to flow easily. Insulators do not allow current to flow easily. Students test different materials by placing them into a simple circuit.
This lesson develops careful testing, observation and classification.
Conductors and insulators
Metals are usually good conductors because they contain charges that can move freely.
Materials such as plastic, rubber, glass and dry wood are usually insulators because charges cannot move through them easily.
Activity - Testing conductors and insulators
Apparatus
- Simple circuit with cell, bulb and wires.
- Two test leads with exposed metal ends.
- At least 20 objects made from different materials.
Procedure
- Build a simple circuit with a gap in it.
- Place each test object into the gap.
- Record whether the bulb lights.
- Classify each object as a conductor or an insulator.
- Look for patterns in the results.
Summary
- Conductors allow current to flow freely.
- Insulators do not allow current to flow freely.
- Most metals are good conductors.
Check your understanding
- What is a conductor?
- What is an insulator?
- Why are metals often used for wires?
Teacher notes & learning objectives
- LO1 - Classify materials as conductors or insulators.
- LO2 - Use a simple circuit as a testing device.
- LO3 - Identify patterns in material properties.
Suggested reading: Electricity and Magnetism, p. 47, covering conductors and insulators.
6u2.5 - Voltage and resistance
Voltage is the push and pull that makes charges move around a circuit. Resistance is the opposition to the flow of current.
Students connect earlier observations about bulbs and cells to the ideas of voltage and resistance.
Voltage
A cell or battery maintains a difference between positive and negative charge at its ends. This provides the push and pull that moves mobile negative charges through a conductor.
The unit of voltage is the volt, symbol V.
Resistance
Resistance is a measure of how difficult it is for electric charge to flow through a material or component.
The unit of resistance is the ohm, symbol Ω.
Bulbs, cells and resistance
Adding more cells usually increases the voltage supplied to the circuit.
Adding more bulbs in series usually increases the total resistance of the circuit.
A higher resistance makes it more difficult for current to flow.
Summary
- Voltage is measured in volts.
- Resistance is measured in ohms.
- Increasing voltage can increase current.
- Increasing resistance makes current more difficult to flow.
Check your understanding
- What does voltage do in a circuit?
- What is resistance?
- Why does adding more bulbs in series usually make each bulb dimmer?
Teacher notes & learning objectives
- LO1 - Describe voltage as the push and pull from a cell or battery.
- LO2 - Describe resistance as opposition to current.
- LO3 - Link voltage and resistance to observations from simple circuits.
Suggested reading: Electricity and Magnetism, pp. 48-51, covering voltage and resistance.
6u2.6 - Modelling circuits using PhET
Computer simulations allow circuits to be built quickly and safely. Students use the PhET circuit construction platform to compare real circuits with simulated circuits.
The simulation is also used to reinforce the ideas of voltage, current and resistance.
Activity - PhET circuit construction
Task
- Open the PhET circuit construction platform.
- Construct selected circuits from the earlier practical work.
- Add more cells and observe what changes.
- Add more bulbs and observe what changes.
- Draw each circuit using circuit symbols.
- Answer questions linking the simulation to current, voltage and resistance.
Summary
- Simulations help us test circuit ideas quickly.
- Adding cells changes the voltage supplied to the circuit.
- Adding bulbs changes the total resistance of the circuit.
Check your understanding
- What is one advantage of using a circuit simulation?
- What happens when more cells are added in the same direction?
- What happens when more bulbs are added in series?
Teacher notes & learning objectives
- LO1 - Use a simulation to construct and compare circuits.
- LO2 - Relate simulated circuits to practical circuits.
- LO3 - Explain observations using voltage and resistance.
This can be supported with a worksheet requiring circuit construction, drawings and explanation questions.
6u2.7 - Length of wire investigation
Students investigate how the length of a wire affects the current in a circuit. This provides a practical context for Criterion C, including data collection, graphing and analysis.
The investigation connects the idea of resistance to a measurable variable.
Activity - Length of wire investigation
Research question
How does the length of a wire affect the current flowing in a circuit?
Apparatus
- Variable power supply or cells.
- Ammeter or multimeter.
- Resistance wire.
- Metre ruler.
- Connecting wires and crocodile clips.
Procedure
- Set up a simple circuit containing the wire and an ammeter.
- Measure the current for different lengths of wire.
- Keep the power supply setting the same.
- Record results in a table.
- Plot a graph and describe the pattern.
Connecting length and resistance
A longer wire usually has a greater resistance.
If the voltage stays the same, increasing the resistance usually reduces the current.
Summary
- Wire length can affect resistance.
- Longer wires usually make it more difficult for current to flow.
- Graphs help show patterns in experimental data.
Check your understanding
- What is the independent variable in the length of wire investigation?
- What is the dependent variable?
- Why should the power supply setting be kept constant?
Teacher notes & learning objectives
- LO1 - Plan and carry out a simple Criterion C investigation.
- LO2 - Collect current data for different wire lengths.
- LO3 - Present and analyse results using a graph.
Demonstration idea before the investigation: use an ammeter, variable power supply and a scrub sponge wire filament to show the effect of too much current and connect this to safety.
6u2.8 - Series and parallel circuits
Components can be connected in series or in parallel. These arrangements behave differently when components are added, removed or broken.
Students construct circuits where one bulb can stop working while another bulb remains lit.
Series circuits
In a series circuit, components are connected in one loop. If the loop is broken, all components stop working.
Parallel circuits
In a parallel circuit, components are connected in separate branches. If one branch is broken, current can still flow through another branch.
Activity - Series and parallel construction
Task
- Build a circuit with two bulbs in series.
- Remove or unscrew one bulb and observe what happens.
- Build a circuit with two bulbs in parallel.
- Remove or unscrew one bulb and observe what happens.
- Draw circuit diagrams for both arrangements.
Summary
- Series circuits have one path for current.
- Parallel circuits have more than one path for current.
- Parallel circuits allow some components to work even when another branch is broken.
Check your understanding
- What is a series circuit?
- What is a parallel circuit?
- Why are lights in homes usually connected in parallel rather than in series?
Teacher notes & learning objectives
- LO1 - Construct series and parallel circuits.
- LO2 - Compare the effect of removing a bulb from each type of circuit.
- LO3 - Explain why parallel circuits are useful in everyday electrical systems.
Suggested reading: Electricity and Magnetism, pp. 64-65, covering series and parallel circuits.
6u2.9 - Circuit games and applications
Students apply their knowledge of circuits by designing and building simple electric games. This develops practical construction skills and allows students to test how circuits can be used in creative ways.
The activities can include a quiz game project and a maze game using foil contacts and a buzzer.
Project - Quiz game
Structure
- Day 1 - Introduction, teams, sample games, topic choice and question planning.
- Day 2 - Construction of the quiz game.
- Day 3 - Complete construction, test other groups' games and complete an evaluation sheet.
Activity - Maze game
Students build a simple circuit game in which a buzzer sounds if a metal loop touches either side of a foil maze.
Suggested construction
- Attach foil to paper or card and cut it into a maze shape.
- Connect the foil to a simple buzzer circuit.
- Use a wire loop as the moving contact.
- The buzzer should sound when the loop touches the foil.
Summary
- Circuits can be used to make games and warning systems.
- A switch can be made when two conducting materials touch.
- Testing and improving a circuit is part of the design process.
Check your understanding
- How does the maze game act like a switch?
- Why is foil useful in this type of circuit?
- What could you improve if your circuit only worked sometimes?
Teacher notes & learning objectives
- LO1 - Apply circuit knowledge to a design task.
- LO2 - Build, test and improve a working circuit product.
- LO3 - Evaluate another group's product using agreed criteria.
Homework option: circuit drawing practice from the Electricity workbook document, p. 3.
6u2.10 - Electricity in society
Electricity is essential in modern society. Students consider what would happen if power was lost in important places such as a hospital, school or supermarket.
This lesson encourages students to connect science understanding with real-world consequences and possible solutions.
Activity - Blackout challenge
Scenario
A location loses electrical power. Students consider the effects after one hour, one day and one week.
Possible locations
- Hospital.
- School.
- Supermarket.
- Home.
- Airport or train station.
Task
- Identify the most serious problems caused by the power loss.
- Suggest possible short-term and long-term solutions.
- Create a poster or presentation explaining the scenario.
- Present the ideas to the class.
Criterion D research - Scientists and electricity
Students research a scientist connected with electricity or magnetism and prepare an article or report.
Suggested process
- Introduce the scientist article task.
- Research different scientists and select one.
- Demonstrate source documentation using MLA in Word.
- Use class time and homework time to develop the article.
Summary
- Electricity is important for safety, communication, food storage, healthcare and transport.
- Power loss has different consequences depending on the time scale.
- Scientific developments are linked to the work of many different scientists.
Check your understanding
- Why would a hospital be seriously affected by a blackout?
- What systems could reduce the impact of a power cut?
- Why is it important to document sources in a research article?
Teacher notes & learning objectives
- LO1 - Explain the importance of electricity in society.
- LO2 - Identify problems and solutions in a blackout scenario.
- LO3 - Support Criterion D research with appropriate source documentation.
The original SoW used class numbers rather than final lesson numbers. This version consolidates the sequence into ten lesson blocks for the unit page.
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