How switches work · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

How switches work

Science · Energy · ages 8-9
Name ______________________   Date ____________

  1. What happens when a switch is open?

    • Current stops flowing
    • Current flows faster
    • Nothing changes

  2. A closed switch lets current flow through the circuit.

    Circle one:   True   False

  3. Which switch position lets a bulb light up?

    • Open
    • Closed
    • It doesn't matter

  4. You flip the wall switch and the lamp turns on. What position is the switch in now?

    • Closed
    • Open
    • Unplugged

  5. Maya's buzzer will not sound. She checks and finds the switch is open. What should she do to make the buzzer sound?

    • Press the buzzer harder
    • Add more wires
    • Close the switch

  6. Every switch in your home works by opening and closing a circuit.

    Circle one:   True   False

  7. A doorbell circuit has a battery, a buzzer, and a button that acts as the switch. Someone presses the button, closing the switch. What happens?

    • The battery stops working
    • The buzzer stays silent because the circuit is broken
    • The buzzer sounds because the circuit is now complete

  8. Ben says: "When I open the switch, more current flows and the bulb gets brighter." What is wrong with what Ben said?

    • Opening the switch makes the bulb brighter, not dimmer
    • Opening a switch stops the current completely, so the bulb goes dark
    • Opening the switch has no real effect on the bulb
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Answer key

For grown-ups. Fold this page away before handing over the rest.

How switches work W1-mt_Hah24nbToi-s1

  1. Current stops flowing · Opening the switch leaves a gap, so current cannot flow and everything connected turns off.
  2. True · Closing the switch fills the gap in the wire, so current can flow all the way around.
  3. Closed · A closed switch completes the loop, letting current reach the bulb.
  4. Closed · If the lamp is on, the circuit must be complete, which means the switch is closed.
  5. Close the switch · Closing the switch fills the gap in the circuit, so current can reach the buzzer and it sounds.
  6. True · Light switches, buzzer buttons, and doorbells all work the same way: closing them completes a circuit.
  7. The buzzer sounds because the circuit is now complete · Pressing the doorbell button closes the switch, completing the circuit so the buzzer sounds.
  8. Opening a switch stops the current completely, so the bulb goes dark · Opening a switch breaks the circuit completely. It does not make the bulb brighter. It turns the bulb off.
Worksheet · LightMySky