Simple Electric Circuits
Lesson preview: the Mini Lesson and Vocabulary are open to everyone. Guided practice, exercises, the parent checklist and the printable PDF worksheet come with full access (free 7-day trial or membership).
What you will learn
- 1Name the key components of a simple electric circuit
- 2Explain the role of each component in allowing current to flow
- 3Distinguish between an open circuit and a closed circuit
Mini Lesson
Electricity flows through a path called a circuit. A simple circuit has four key components: a battery (power source), wires (path), a switch (control), and a bulb (output). For electricity to flow, the circuit must be a complete, unbroken loop — a closed circuit.
The Four Components and the Complete Loop
- Battery — stores chemical energy and converts it into electrical energy to power the circuit.
- Wire — a metal conductor that carries the electric current from one component to the next.
- Switch — opens or closes the circuit. Open switch = no current flows. Closed switch = current flows.
- Bulb — converts electrical energy into light and heat when current passes through its filament.
- Closed circuit — the complete loop is formed; current flows and the bulb lights up.
Open vs Closed Circuit
- Open circuit: the loop is broken (e.g. switch is open). Current cannot flow, so the bulb is OFF.
- Closed circuit: the loop is complete. Current flows from battery, through wire, switch, and bulb, and back to battery. Bulb is ON.
- A break anywhere in the circuit stops the current — even a loose wire will turn off the bulb.
Words to know
Circuit
A complete, closed path through which electric current flows
e.g. A simple circuit powers a flashlight bulb.
Battery
A device that stores chemical energy and converts it to electrical energy
e.g. A 1.5V battery powers a small flashlight.
Conductor
A material that allows electric current to pass through it easily
e.g. Copper wire is a good conductor.
Switch
A device that opens or closes a circuit to control the flow of current
e.g. Flipping a switch turns a light on or off.
Open circuit
A circuit with a gap or break so no current flows
e.g. An open switch creates an open circuit.
Closed circuit
A complete, unbroken circuit through which current can flow
e.g. Closing the switch completes the circuit.
Think of the circuit like a running track. The runners (electrons) can only run if the track is a complete loop. Any gap stops them completely.
Unlock the full HSEA system for 7 days.
Add your first kid profile and your 7 days start: every lesson in every grade, saved progress for each child. Nothing to set up, no card required, nothing to cancel.
- ✓ All 1,880 lessons, Grades 1–6, every subject
- ✓ Profiles + saved progress for every kid
- ✓ Printable lessons with answer key