Measuring Voltage and Current

Overview

In this ninth lesson of Circuits, Current, and Creativity, students use circuit diagrams and observations to distinguish voltage from current. Working in teams, they safely measure or analyze teacher-provided measurements from basic 9V circuits, record results with correct units, and explain where each measurement belongs in a circuit.

Learning intentions

Students will be able to:

• Identify voltage and current as different measurable properties of a circuit.
• Use or interpret a multimeter safely to measure voltage and current.
• Record observations in an organized data table using volts and amperes.
• Connect measurement locations to a labeled circuit diagram and explain their reasoning.

Success criteria

• I can explain what voltage and current measure in a circuit.
• I can identify volts (V) and amperes (A) as the correct units.
• I can show that a voltmeter is connected across components and an ammeter is placed in the current path.
• I can record measurements accurately and support a conclusion with data.

Curriculum links

• Washington State science learning: students plan and carry out safe investigations, collect and analyze data, and use evidence to communicate explanations about electrical systems.
• Reading in science and technical subjects: students describe the sequence of steps in a procedure and follow technical directions accurately.
• Reading in science and technical subjects: students integrate information from circuit diagrams, measurement tables, and hands-on observations.
• Mathematical reasoning: students interpret positive rational quantities, compare measurements, and use units consistently when describing real-world quantities.

Lesson structure (40 minutes)

1. 0–5 min · Hook and prior knowledge. Display a simple 9V battery, lamp, wires, and two multimeter images using the hook and comparison slides. Ask: “If a circuit has 9 volts, does that mean 9 amps are flowing?” Students make an individual prediction, then share with a partner and identify what evidence would help answer the question.

2. 5–12 min · Direct instruction and safety. Use the measurement and safety slides to define voltage as electrical potential difference, measured in volts (V), and current as the rate of charge flow, measured in amperes (A). Model the key difference: a voltmeter connects across a component, while an ammeter must be placed in the circuit path. Demonstrate that students must use teacher-approved settings, never connect an ammeter directly across a battery, keep leads in the correct ports, and ask before changing a connection. Students annotate the two diagrams on the circuit measurement worksheet and repeat the safety rule with a partner.

3. 12–17 min · Teacher model. Build or display a basic battery-lamp circuit and model one voltage measurement, narrating each step without passing equipment around. Show how to read the display, identify the unit, and record the result in a table. Then show a current measurement or a teacher-provided current reading, emphasizing that the circuit must be opened before placing an ammeter in series. Students identify the measurement type, location, and unit from two projected examples.

4. 17–30 min · Team investigation. Place students in teams of four with roles: equipment manager, circuit checker, recorder, and safety reporter. Teams use teacher-approved 9V circuits or the prepared readings at stations. They complete the table on the circuit measurement worksheet, recording at least two voltage observations and two current observations, the component or circuit location, the numerical value, and the unit. Students draw or label where each meter is connected on the circuit diagram. The teacher circulates, checks connections before testing, and asks, “What is your meter measuring, and why is it connected there?”

5. 30–36 min · Data discussion and error analysis. Return to the data discussion slides. Teams compare one voltage and one current result with another team, looking for differences in readings, units, or measurement locations. Invite students to explain why voltage readings may be taken across a battery or lamp and why current readings must be taken in the path of the circuit. Students revise one table entry or diagram if their evidence shows an error.

6. 36–40 min · Exit assessment and preview. Display the final prompt using the plenary slide. Students complete the final section of the circuit measurement worksheet: “A student connects an ammeter across a 9V battery. What is wrong, and how should the connection change?” They also state one difference between voltage and current and identify both units. Collect worksheets as students leave.

Resources

• the complete measurement and safety slide deck
• the circuit measurement worksheet
• Teacher-approved 9V batteries or battery holders
• Small lamps, resistors, wires, and switches
• Digital multimeters, or teacher-provided voltage and current readings
• Safety goggles
• Visible timer and board markers
• Completed sample circuit diagram for teacher modeling

Assessment

• During instruction, listen for accurate use of “across” for voltage and “in the path” or “in series” for current. Check students’ diagram annotations before equipment is used.
• During team work, review tables for correct units, clearly labeled locations, plausible readings, and complete observations. Ask individual students to explain one recorded result.
• Use the exit response to identify students who confuse voltage and current, omit units, or do not understand safe meter placement. Begin the next lesson with a brief correction based on these patterns.

Differentiation

• Provide a partially completed circuit diagram, a word bank containing voltage, current, volts, amperes, across, and series, and sentence starters such as “The meter is connected ___ because it measures ___.”
• Pair students strategically and assign roles so students with fine-motor, reading, or attention needs can contribute through checking, recording, explaining, or handling equipment with support.
• For English learners, use labeled visual diagrams, gestures for “across” and “through,” partner rehearsal, and repeated modeling before independent work.
• For students ready for greater challenge, ask them to compare two readings, identify a possible source of error, and explain how the circuit diagram and data table together support their conclusion.