Activity 01
Verification Lab: Ohm's Law Graph
Provide batteries, resistors, wires, ammeter, and voltmeter. Students connect circuit, vary resistance across three values, measure voltage and current pairs, then plot V against I on graph paper. Discuss slope as resistance and check linearity.
How can a simple mathematical relationship between voltage, current, and resistance help engineers design safe and effective electrical circuits?
Facilitation TipDuring the Verification Lab, circulate with a multimeter and ask each pair to predict the slope of their V-I graph before they collect data, forcing a think-first approach.
What to look forPresent students with three simple circuit scenarios. For each, provide two values (e.g., voltage and resistance) and ask them to calculate the missing third value (current) using Ohm's Law. Include one scenario where they must calculate resistance.
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Activity 02
Prediction Pairs: Voltage Doubling
Pairs sketch circuit with fixed resistor and single battery, predict and calculate current. Add second battery in series, measure new current, compare to prediction. Record percentage error and reasons for differences.
What would happen to the current in a circuit if you doubled the voltage while keeping resistance constant?
Facilitation TipFor Prediction Pairs, give one student the voltage values and the other the resistance, then have them swap roles after each prediction to reinforce the shared calculation.
What to look forPose the question: 'Imagine you have a light bulb rated for 120V and 25W. If you accidentally connect it to a 240V power source, what would happen to the current and why? Use Ohm's Law and power calculations to justify your prediction.'
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Activity 03
Design Challenge: Safe Circuits
Small groups design circuit for 1.5 A max current using 12 V supply and available resistors. Calculate required R, build and test with multimeter. Adjust if current exceeds limit, present final design.
How do engineers use the relationship between voltage, current, and resistance to predict whether a component will be damaged by too much current?
Facilitation TipAt the Series Station Rotation, place a high-resistance resistor in one tray and ask students to explain why the current reading is lower than expected before they check their calculations.
What to look forProvide students with a simple circuit diagram including a battery, a resistor, and an ammeter. Ask them to calculate the current flowing through the circuit if the voltage is 6V and the resistance is 2 Ohms. Then, ask them to explain in one sentence what would happen to the current if the resistance were doubled.
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Activity 04
Series Station Rotation
Set stations for calculating total R, expected I, and V drop per resistor in series. Groups rotate, build one circuit per station, measure to verify calculations, log data in shared table.
How can a simple mathematical relationship between voltage, current, and resistance help engineers design safe and effective electrical circuits?
Facilitation TipIn the Design Challenge, require teams to submit a labeled circuit sketch with calculated current before they receive any components, ensuring they apply the law before building.
What to look forPresent students with three simple circuit scenarios. For each, provide two values (e.g., voltage and resistance) and ask them to calculate the missing third value (current) using Ohm's Law. Include one scenario where they must calculate resistance.
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Generate Complete Lesson→A few notes on teaching this unit
Start with simple circuits so students can see the numbers change as they adjust one variable at a time. Avoid rushing to abstract equations; let the measurements build the relationship first. Research shows that students who physically measure and graph the data retain the inverse relationship between resistance and current far better than those who only solve worksheets.
By the end of these activities, students should confidently use V = I × R to calculate missing values and explain why doubling one variable shifts the others in a predictable way. They should also distinguish ohmic from non-ohmic components and describe how voltage divides in series circuits.
Watch Out for These Misconceptions
During Verification Lab: Ohm's Law Graph, watch for students who assume the line must pass through the origin without checking the data. Their graphs may start above zero due to contact resistance, masking the true relationship.
Ask students to measure and record the intercept, then guide them to identify it as contact resistance. Have them subtract this offset before calculating the slope to reinforce careful measurement.
During Prediction Pairs: Voltage Doubling, watch for students who think doubling the voltage doubles the resistance as well.
Have pairs plot their predicted and measured currents for 3 V, 6 V, and 9 V on the same axes, then draw a trend line to show the direct proportionality between V and I when R is constant.
During Design Challenge: Safe Circuits, watch for students who assume any resistor will limit current safely without calculating the required value.
Require teams to calculate the minimum resistor value using Ohm’s Law before selecting parts, and have them verify their choice with a multimeter during testing.
Methods used in this brief