Physics · Year 12

Active learning ideas

Current, Resistance, and Ohm's Law

Active learning works for this topic because students must directly manipulate circuits to see how current and resistance behave in real time. Hands-on labs and challenges turn abstract equations like V = IR into tangible evidence, making misconceptions visible and correctable through experience.

• ACARA Content Descriptions
• AC9SPU06

• 35–50 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Inquiry Circle
• 50 min · Small Groups

Inquiry Lab: Verifying Ohm's Law

Students connect a battery, variable resistor, ammeter, and voltmeter in series. They adjust resistance across five values, record voltage and current pairs, then plot a V-I graph to confirm linearity and calculate resistance from the slope. Groups discuss sources of error like internal resistance.

Explain how the properties of a material influence its electrical resistance.

Facilitation Tip

During the Inquiry Lab: Verifying Ohm's Law, have students record voltage and current values in a shared class table to build consensus on expected proportionality.

What to look for

Present students with a circuit diagram containing known voltage and resistance values. Ask them to calculate the current using Ohm's Law. Then, pose a question: 'If the resistance were doubled, what would happen to the current, assuming voltage remains constant?'

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Activity 02

• Stations Rotation
• 45 min · Small Groups

Stations Rotation: Resistance Factors

Set up stations for length (fixed wire gauge, vary length), area (fixed length, vary gauge), material (compare copper, nichrome), and temperature (hot vs. cold wire). Groups measure resistance at each using a multimeter, record data, and graph relationships.

Predict the current in a simple circuit using Ohm's Law.

Facilitation Tip

For the Station Rotation: Resistance Factors, set up each station with clear material samples and a multimeter so students focus on measurement without setup delays.

What to look for

Provide students with a table of materials and their resistivities. Ask them to identify which material would be best suited for a heating element and which for an electrical insulator, justifying their choices based on resistivity values.

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Activity 03

• Inquiry Circle
• 35 min · Pairs

Pairs Challenge: Circuit Prediction

Pairs receive components and a target current value. They calculate required resistance using Ohm's Law, assemble the circuit, measure actual current, and adjust iteratively. Pairs present their design choices and results to the class.

Design an experiment to determine the resistivity of an unknown conductor.

Facilitation Tip

In the Pairs Challenge: Circuit Prediction, provide colored pens for students to annotate circuits with expected current and voltage drops before building them.

What to look for

Facilitate a class discussion on the experiment to determine resistivity. Ask: 'What are the key variables you would need to control? What potential sources of error might you encounter when measuring the length and diameter of a wire?'

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Activity 04

• Inquiry Circle
• 40 min · Whole Class

Whole Class: Resistivity Hunt

Provide unknown wires; class designs a shared protocol to measure length, diameter, resistance, then compute resistivity. Compare results across groups and discuss precision in diameter measurements using calipers.

Explain how the properties of a material influence its electrical resistance.

Facilitation Tip

During the Whole Class: Resistivity Hunt, assign each group a different material so the class collectively builds a resistivity database to compare against reference values.

What to look for

Present students with a circuit diagram containing known voltage and resistance values. Ask them to calculate the current using Ohm's Law. Then, pose a question: 'If the resistance were doubled, what would happen to the current, assuming voltage remains constant?'

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

A few notes on teaching this unit

Teach this topic by starting with simple circuits and increasing complexity gradually. Use analogies like water flow to explain current and resistance, but transition quickly to real data to avoid over-reliance on metaphors. Emphasize the limits of Ohm's Law by including non-ohmic components early, so students recognize when equations don’t apply. Research shows frequent, low-stakes data collection reduces anxiety and improves retention of circuit concepts.

Successful learning looks like students predicting circuit outcomes using Ohm's Law, adjusting variables with purpose, and articulating why changes in resistance or voltage alter current. They should explain their reasoning with both calculations and experimental evidence.

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Watch Out for These Misconceptions

• During the Inquiry Lab: Verifying Ohm's Law, watch for students interpreting decreasing current readings after a resistor as evidence that current is 'used up' in the circuit.

  Use the shared class data table to highlight that voltage drops across resistors, not current. Have students calculate voltage drops at each resistor to reinforce the constant current in series circuits.

• During the Station Rotation: Resistance Factors, watch for students predicting that thicker wires always increase resistance because they 'take up more space.'

  Set up the multimeter on a fixed voltage setting and have students measure current through wires of different gauges. Guide them to observe that thicker wires allow higher current, demonstrating lower resistance due to increased cross-sectional area.

• During the Pairs Challenge: Circuit Prediction, watch for students assuming Ohm's Law applies to all devices, including light bulbs and diodes.

  Provide a filament bulb and a diode in the challenge kits. Ask students to predict and then measure the current at different voltages, prompting discussion of non-ohmic behavior when their predictions fail.

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Methods used in this brief

• Inquiry Circle
• Stations Rotation