Physics · Grade 11

Active learning ideas

Lab: Ohm's Law and Resistors

Active learning works for Ohm's Law because students directly manipulate circuit components and observe real-time changes in voltage and current. This hands-on approach clarifies abstract concepts through measurable, repeatable results that build confidence and conceptual understanding.

• Ontario Curriculum Expectations
• HS-PS2-5

• 30–50 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Inquiry Circle
• 45 min · Pairs

Circuit Building: Voltage Variation

Pairs connect a resistor, ammeter, and variable power supply in series. They set voltages from 1V to 10V in 1V steps, measure current each time, and plot V versus I on graph paper. Discuss the slope as resistance value.

Evaluate the linearity of the relationship between voltage and current for a resistor.

Facilitation Tip

During 'Circuit Building: Voltage Variation', ensure students measure voltage directly across the resistor, not just the power supply, to avoid confusing total voltage with voltage drop.

What to look for

Provide students with a data table of voltage and current measurements for a resistor. Ask them to: 1. Calculate the resistance for three different data points. 2. State whether the voltage-current relationship appears linear based on their calculations. 3. Write one sentence explaining their reasoning.

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

Activity 02

• Inquiry Circle
• 35 min · Small Groups

Resistor Comparison Stations

Set up stations with three resistors and fixed 6V supply. Small groups measure current for each, calculate resistance using V=IR, and rotate to verify results. Compare group averages class-wide.

Analyze how different resistors affect the current in a circuit.

Facilitation Tip

In 'Resistor Comparison Stations', assign each group a different resistor value so data can be pooled later for whole-class analysis of trends.

What to look for

During the lab, circulate and ask students: 'If you double the voltage across this resistor, what do you predict will happen to the current? Explain your answer using Ohm's Law.' Listen for correct application of the proportional relationship.

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

Activity 03

• Inquiry Circle
• 50 min · Pairs

Unknown Resistor Challenge

Provide an unknown resistor. Individuals or pairs design a procedure: vary voltage, measure currents, graph, and extrapolate resistance from slope. Share designs and test one peer method.

Design an experiment to determine the resistance of an unknown component.

Facilitation Tip

For the 'Unknown Resistor Challenge', provide a multimeter for verification but encourage students to use Ohm's Law calculations first to build reasoning skills.

What to look for

Pose the question: 'Imagine your graph of voltage versus current for a resistor is not a perfectly straight line. What are two possible reasons for this deviation from Ohm's Law in a real-world experiment?' Guide students to consider measurement error and component behavior.

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

Activity 04

• Inquiry Circle
• 30 min · Whole Class

Whole Class Data Pool

All students collect V-I data for one resistor, enter into shared spreadsheet. Class analyzes combined graph for linearity, identifies outliers, and recalculates average resistance.

Evaluate the linearity of the relationship between voltage and current for a resistor.

Facilitation Tip

During 'Whole Class Data Pool', ask students to compare their resistor's slope to others, prompting discussion on unit consistency and graph interpretation.

What to look for

Provide students with a data table of voltage and current measurements for a resistor. Ask them to: 1. Calculate the resistance for three different data points. 2. State whether the voltage-current relationship appears linear based on their calculations. 3. Write one sentence explaining their reasoning.

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

A few notes on teaching this unit

Teach Ohm's Law by having students focus on one variable at a time, starting with voltage changes while keeping resistance constant. Avoid overwhelming students with parallel or series circuits at this stage. Use real-time data to correct misconceptions, such as attributing non-linear graphs to resistor behavior rather than measurement error. Research shows that students grasp proportional relationships when they see immediate visual feedback from their circuits.

Successful learning looks like students accurately recording voltage and current values, plotting linear graphs, and correctly explaining how resistance affects current. They should confidently apply Ohm's Law to predict and justify changes in circuit behavior during each activity.

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Watch Out for These Misconceptions

• During 'Circuit Building: Voltage Variation', watch for students assuming Ohm's Law applies to non-ohmic components like bulbs.

  Ask students to replace the resistor with a small bulb, measure voltage and current, and plot the graph. Compare the linear resistor graph to the bulb's curve, then discuss why real devices often deviate from ideal behavior.

• During 'Resistor Comparison Stations', watch for students ignoring temperature effects on resistance.

  Have students run the circuit for two minutes and record current every 30 seconds. Ask them to explain why the current drifts slightly and refer to the resistor's datasheet to discuss temperature coefficients.

• During 'Unknown Resistor Challenge', watch for students assuming equal voltage means equal current through different resistors.

  Ask students to calculate the expected current for each resistor using Ohm's Law and compare their predictions to measured values. Use this discrepancy to highlight the inverse relationship between resistance and current.

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Methods used in this brief

• Inquiry Circle