Identifying Inputs, Processes, and Outputs

This lesson covers how to identify inputs, processes, and outputs when solving problems, as required by OCR J277 Section 2.1. This is a fundamental skill in computational thinking that helps you understand what a system needs to do before you start designing it.

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The Input-Process-Output (IPO) Model

Every computer system and algorithm can be described using the Input-Process-Output (IPO) model:

Stage	Description	Example (Calculator)
Input	Data that enters the system	The numbers to be calculated and the operation (+, -, x, /)
Process	What the system does with the input	Performs the arithmetic calculation
Output	The result produced by the system	The answer is displayed on screen

This simple model applies to every algorithm and system, from a basic calculator to a complex weather forecasting system.

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Identifying Inputs

Inputs are the data that a system receives from the user or another source. When analysing a problem, ask: "What data does the system need to work with?"

Types of Input

Input Type	Description	Example
User input	Data entered by a person	Typing a search query, entering a password
Sensor input	Data from electronic sensors	Temperature reading, motion detection
File input	Data read from a stored file	Loading a saved game, reading a CSV file
Network input	Data received from another device	Receiving an email, streaming video
System input	Data from the computer's own systems	Current date and time, mouse position

Example: Online Shopping Checkout

Input	Source
Items in basket	User selection (during browsing)
Delivery address	User input (form)
Payment details	User input (form)
Discount code	User input (optional)
Current date	System (for delivery estimate)
Stock levels	Database

OCR Exam Tip: When identifying inputs, include ALL data the system needs — not just what the user types. Remember to consider data from files, databases, sensors, and the system itself. Each input should be specific (e.g. "the user's postcode" not just "information").

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Identifying Processes

Processes are the operations performed on the inputs to produce the outputs. When analysing a problem, ask: "What does the system need to do with the data?"

Types of Process

Process Type	Description	Example
Calculation	Mathematical operations	Calculating total price, averaging scores
Comparison	Checking if values meet conditions	Is the password correct? Is the student over 16?
Sorting	Arranging data in order	Sorting search results by relevance
Searching	Finding specific data	Looking up a customer record by ID
Validation	Checking that input is reasonable	Is the age between 0 and 150? Is the email format valid?
Storage	Saving data for later use	Writing a record to a database
Transformation	Converting data from one form to another	Converting temperature from Celsius to Fahrenheit

Example: Online Shopping Checkout

Process	Detail
Calculate subtotal	Add up the prices of all items in the basket
Apply discount	If a valid discount code is entered, reduce the total
Calculate delivery cost	Based on delivery address and delivery speed
Calculate total	Subtotal + delivery - discount
Validate payment	Check that card details are valid and funds are available
Update stock	Reduce stock levels for purchased items
Generate order ID	Create a unique identifier for the order

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Identifying Outputs

Outputs are the results produced by the system after processing the inputs. When analysing a problem, ask: "What does the system need to produce or display?"

Types of Output

Output Type	Description	Example
Screen display	Information shown to the user	Search results, error messages, graphs
Printed output	Physical documents	Receipts, reports, invoices
Sound	Audio output	Alerts, music, text-to-speech
File output	Data written to a file	Saving a document, exporting a report
Network output	Data sent to another device	Sending an email, uploading a file
Physical action	Controlling a device	Turning on a light, opening a barrier

Example: Online Shopping Checkout

Output	Destination
Order confirmation page	Screen (user)
Order confirmation email	Email (user)
Order details	Database (company)
Payment receipt	Email (user)
Updated stock levels	Database (internal)
Dispatch notification	Email (warehouse)

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Worked Examples

Example 1: School Attendance System

Category	Details
Inputs	Student ID, date, attendance status (present/absent/late), time of arrival (if late)
Processes	Record attendance for each student, calculate attendance percentage, check for persistent absence (below 90%), identify patterns of absence
Outputs	Daily register, attendance reports for form tutors, alerts for persistent absence, letters to parents, attendance statistics for the school

Example 2: Temperature Monitoring System

Category	Details
Inputs	Temperature readings from sensor (every 5 minutes), minimum and maximum thresholds set by user
Processes	Compare current temperature to thresholds, calculate average temperature over time, detect if temperature is rising or falling, log all readings
Outputs	Current temperature display, alarm/alert if threshold exceeded, graph of temperature over time, log file of all readings

Example 3: Password Checker

Category	Details
Inputs	Username, entered password, stored password hash
Processes	Hash the entered password, compare hashed password with stored hash, check number of failed attempts
Outputs	Access granted or denied message, account locked warning (after too many failed attempts), timestamp of login attempt (logged)

OCR Exam Tip: In the exam, you may be asked to identify inputs, processes, and outputs for a given scenario. Present your answer clearly — use a table or bullet points. Make sure your processes explain WHAT the system does with the inputs, and your outputs are the RESULTS of those processes. Do not just repeat the inputs as outputs.

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Summary

The Input-Process-Output model is a fundamental tool for understanding and designing systems. Inputs are the data the system receives, processes are what the system does with that data, and outputs are the results produced. For the OCR J277 exam, practise identifying all three components for different real-world scenarios, and remember to be specific about each item.

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Worked Example: Automatic Greenhouse Controller

A school is building a controller for its greenhouse. The controller reads the current temperature and soil moisture every minute, decides whether to turn on the heater and the irrigation pump, and logs the readings to a file. The gardener has set target bands: temperature between 18°C and 26°C, soil moisture between 40% and 70%.

Step 1 — List all inputs, being specific about the source.

Input	Source	Type
Current temperature	Temperature sensor	Real (°C)
Current soil moisture	Moisture sensor	Real (%)
Target minimum temperature	Settings file	Real
Target maximum temperature	Settings file	Real
Target minimum moisture	Settings file	Real
Target maximum moisture	Settings file	Real
Current date and time	System clock	DateTime