---
title: "Systems: Input, Process, Output"
description: "Any made thing can be drawn as a block diagram: what goes in, what is done to it, what comes out. Drawing it that way shows where a fault must be before anything is opened up."
canonical: https://lightmysky.com/learn/design-and-technology/systems-input-process-output-mt_bMNTQ-3a_u
source: https://lightmysky.com/learn/design-and-technology/systems-input-process-output-mt_bMNTQ-3a_u.md
retrieved: 2026-09-12
---

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# Systems: Input, Process, Output

Any made thing can be drawn as a block diagram: what goes in, what is done to it, what comes out. Drawing it that way shows where a fault must be before anything is opened up.

Subject: Design & Technology · Area: Designing & Making · Ages 12 to 14
Page: https://lightmysky.com/learn/design-and-technology/systems-input-process-output-mt_bMNTQ-3a_u

## Ready when they can

- Draw a block diagram for an everyday product with the three stages labelled
- Use a block diagram to say which stage a described fault must be in
- Explain what feedback adds to a system, using a thermostat or a cruise control
- Say why the same diagram fits a kettle and a phone app

## Lesson: Every made thing is a system

You can draw any made thing as three boxes. What goes in, what is done to it, and what comes out. That drawing is a block diagram of the system.

**Example.** Take a kettle. Cold water and electricity go in, heating is the process, and hot water comes out. A phone app fits the same drawing: your taps and data go in, the program processes them, and the screen shows the result.

Some systems add feedback, where part of the output loops back to steer the input. A thermostat feels the room cooling and switches the heater back on. Cruise control feels the car slowing and feeds in more fuel.

**Tip.** When a product fails, ask which stage holds the fault before you open anything. Nothing coming in means an input fault. Right input but wrong result means the process stage. A good result badly delivered means the output stage.

**Recap.** Map every product to input, process, and output, then trace faults stage by stage, watching for feedback loops.

## Practice

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

## Needs first

- [Drawing a Design So Someone Else Can Build It](https://lightmysky.com/learn/design-and-technology/drawing-a-design-so-someone-else-can-build-it-mt_8ezErqUhZw)
- [Electronics in a Product: Switch, Sensor, Output](https://lightmysky.com/learn/design-and-technology/electronics-in-a-product-switch-sensor-output-mt_KNLW4qke5J)

## Opens up

- [The Whole Life of a Product](https://lightmysky.com/learn/design-and-technology/the-whole-life-of-a-product-mt_hyBZiDvDoX)