Activity 01
Circuit Building: Resistor I-V Graph
Pairs connect a resistor, ammeter, and variable power supply in series with a voltmeter across the resistor. They record I and V for voltages from 0-6V in 1V steps, plot the graph, and calculate resistance from gradient. Discuss why the line is straight.
Differentiate between ohmic and non-ohmic components based on their I-V graphs.
Facilitation TipDuring Graph Matching Relay, rotate groups only after each team has justified at least two graph-component matches to encourage thorough reasoning.
What to look forProvide students with three different I-V graphs, each representing an ohmic resistor, a filament lamp, and a diode. Ask them to label each graph and write one sentence justifying their classification for each component.
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Activity 02
Stations Rotation: Component Characteristics
Set up stations for resistor, lamp, and diode. Small groups measure I-V data at each for 10 minutes, swap components, then combine class data to plot shared graphs. Compare shapes and predict resistance changes.
Explain why the resistance of a filament lamp increases with temperature.
What to look forPose the question: 'Why does the resistance of a filament lamp increase as it gets hotter?' Encourage students to refer to their experimental data and the shape of the I-V graph to explain the physical reason behind this change.
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Activity 03
Prediction Challenge: Diode Forward Bias
Individuals sketch expected I-V for a diode from description, then test in circuit with 0.2V steps from 0-1V. Groups share predictions vs results, explaining threshold voltage. Extend to reverse bias.
Predict the current through a diode given its forward bias voltage.
What to look forGive students a partial I-V graph for a diode. Ask them to extend the graph to show typical behavior in forward bias and reverse bias, and then predict the approximate current if the voltage is increased by 0.5V in the forward bias region.
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Activity 04
Graph Matching Relay
Whole class divides into teams. Teams match printed I-V graphs to components (resistor, lamp, diode) and justify in relay format: one student runs to board per correct match. Debrief curves.
Differentiate between ohmic and non-ohmic components based on their I-V graphs.
What to look forProvide students with three different I-V graphs, each representing an ohmic resistor, a filament lamp, and a diode. Ask them to label each graph and write one sentence justifying their classification for each component.
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Generate Complete Lesson→A few notes on teaching this unit
Teach this topic by letting students experience the mismatch between expectation and reality. Start with resistors to establish the baseline linear relationship, then introduce the lamp and diode to challenge assumptions. Use sequential measurements (e.g., measuring I-V as the lamp heats) to show how conditions alter behavior. Avoid rushing to conclusions; allow time for students to reconcile their observations with their initial ideas.
Success looks like students correctly interpreting I-V graphs and explaining why components behave differently. They should confidently match graphs to components, describe the physical causes behind curvature or flat lines, and use threshold voltage language for diodes. Evidence from their own measurements and discussions should drive their explanations, not just recall.
Watch Out for These Misconceptions
During Circuit Building: Resistor I-V Graph, watch for students assuming all components will produce straight lines through the origin.
After plotting their resistor data, have students overlay a filament lamp’s I-V graph from Station Rotation. Ask them to compare slopes at different voltages to highlight non-linearity and prompt discussion about temperature effects on resistance.
During Station Rotation: Component Characteristics, watch for students treating diodes as if they conduct equally in both directions.
During the diode station, ask students to test forward and reverse bias and immediately plot both sets of data on the same axes. Then, have them present their graphs to the class to emphasise the one-way threshold effect.
During Circuit Building: Resistor I-V Graph, watch for students believing filament lamp resistance decreases when hot because the light is brighter.
Before measuring, ask students to predict how the slope of the I-V graph will change as the lamp heats. After collecting data, pool class results on a whiteboard and discuss how the increasing slope indicates rising resistance.
Methods used in this brief