OCR GCSE Computer Science – Calculating File Sizes | Text, Images & Sound Lesson

OCR GCSE Computer Science – Calculating File Sizes (Full Lesson Pack)
(Also ideal for AQA and Edexcel Computer Science courses)

This fully editable lesson teaches students how to calculate the size of text, image, and sound files, linking directly to the OCR J277 Unit 1.2 – Data Representation topic.
Learners explore real files, practise core exam formulas, and develop an understanding of how storage requirements are derived in bits, bytes, kilobytes, and megabytes.

Lesson objectives

Students will be able to:

Calculate the size of text files using bits per character × number of characters.

Calculate the size of image files using colour depth × resolution.

Calculate the size of sound files using sample rate × duration × bit depth.

Explain how file size, quality, and storage capacity are related.

What’s included

Fully editable Word lesson pack with tasks and examples.

Starter activity – interactive binary conversion game to recap prior knowledge.

Hands-on file activity – create and inspect a .txt file using a hex editor to explore how text is stored.

Worked examples for calculating text, image, and sound file sizes.

Realistic data tasks (icons, wallpapers, 4K images, and audio clips).

Student self-assessment checkpoints (“Is it ok to move on?”).

Plenary reflection to consolidate understanding of key terms: bit, nibble, byte, resolution, colour depth, sample rate.

Why teachers love it

Breaks down tricky file-size calculations into clear, step-by-step problems.

Combines theory with applied tasks using real-world data examples.

Reinforces memory and storage fundamentals through practice and explanation.

Fully editable for differentiated delivery or homework use.

File format

Editable .docx lesson worksheet

Suitable for digital or print delivery

Tags
OCR GCSE Computer Science, J277, Data Representation, Memory and Storage, File Size, Bits, Bytes, Colour Depth, Resolution, Sample Rate, Bit Depth, Sound, Image, Text, KS4 Computing, Computer Science Lesson