---
title: "Electronics in a Product: Switch, Sensor, Output"
description: "Most electrical products are the same three parts: something that decides, something that senses, and something that happens. A switch is a person deciding, a sensor is the product deciding for itself"
canonical: https://lightmysky.com/learn/design-and-technology/electronics-in-a-product-switch-sensor-output-mt_KNLW4qke5J
source: https://lightmysky.com/learn/design-and-technology/electronics-in-a-product-switch-sensor-output-mt_KNLW4qke5J.md
retrieved: 2026-09-12
---

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# Electronics in a Product: Switch, Sensor, Output

Most electrical products are the same three parts: something that decides, something that senses, and something that happens. A switch is a person deciding, a sensor is the product deciding for itself.

Subject: Design & Technology · Area: Designing & Making · Ages 11 to 13
Page: https://lightmysky.com/learn/design-and-technology/electronics-in-a-product-switch-sensor-output-mt_KNLW4qke5J

## Ready when they can

- Sort the parts of a simple product into input, control and output
- Explain the difference between a switch and a sensor in what triggers them
- Name two sensors and what each measures, such as light or temperature
- Sketch a circuit for a stated behaviour, such as a light that comes on when it gets dark

## Lesson: Sense, Decide, Do

Most gadgets share three parts: something senses, something decides, and something happens. Spot the three and you can read any product. In a simple radio the antenna catches waves from the air, the tuner picks the station, and the earpiece makes the sound you hear.

A switch means a person decides, like pressing a torch button. A sensor means the product decides for itself, like a garden lamp that notices dark.

**Example.** A night light that glows at dusk holds a light sensor, a tiny decider, and a lamp. Dark in, choice made, light out.

**Tip.** To sketch a circuit, draw the three in a loop: sense at the start, decide in the middle, and the output at the end.

**Recap.** Sort each part into sense, decide or do, and the product stops feeling like magic.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Mechanisms That Make Things Move](https://lightmysky.com/learn/design-and-technology/mechanisms-that-make-things-move-mt_i6Je5hnxJz)
- [Drawing circuits with proper symbols](https://lightmysky.com/learn/science/drawing-circuits-with-proper-symbols-mt_NzNLYDb9CZ)

## Opens up

- [Systems: Input, Process, Output](https://lightmysky.com/learn/design-and-technology/systems-input-process-output-mt_bMNTQ-3a_u)