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J277 1.2 Data representation consolidation

Part 5 of 5 · J277 1.2.4-1.2.5 · Data representation

The end-of-topic checkpoint for data representation, combining characters, images, sound and compression.

Students will:

  • select the right representation idea for an unfamiliar scenario
  • calculate text, image and sound file sizes with working shown
  • compare lossy and lossless compression in context
  • correct flawed statements about resolution, colour depth and sampling
  • apply knowledge in focused answers and improve them after feedback

Inside: 5 text sections, 4 completion activities, 7 written answers. 23 marks. Suggested teaching time: 40–60 minutes.

Includes a teacher guide with suggested sections, timings and common misconceptions.

Series: J277 1.2.4-1.2.5 · Data representation, part 5 of 5.

Shared by Coding PathwayVerified teacher

  • 16 cells
  • About 45 minutes
  • CC BY-SA 4.0
  • Shared 17 Aug 2026
  • Updated 27 Oct 2026

Preview

The whole resource, exactly as a class sees it. Answers and marking are held back.

Data representation consolidation

Use what you know about characters, images, sound and compression. Show your method where requested, then enter each final value in its own field. For all calculations use 1 KB = 1,000 bytes and ignore headers or metadata. Completion feedback is held for teacher review.

Fill in the blanks4 marks
Answer from memory. (a) Bits per image pixel: Answer 1 (b) Number of image pixels: Answer 2 (c) Sound samples per second: Answer 3 (d) Bits per sound sample: Answer 4
Written answer3 marks

A worldwide messaging service needs names and messages from many writing systems. Explain one benefit of Unicode and one possible effect on storage requirements.

Students type their answer here.

Fill in the blanks1 mark
An uncompressed text file contains 6,000 characters at 8 bits each. Its character-data size is Answer 1 KB.

1. An image calculation

An uncompressed bitmap has 400 × 250 pixels at a colour depth of 8 bits per pixel.

Written answer2 marks

Show your method for calculating this image's pixel-data size in KB.

Students type their answer here.

Fill in the blanks1 mark
The final size of this image's uncompressed pixel data is Answer 1 KB.

2. A sound calculation

An uncompressed mono recording lasts 20 seconds. Its sample rate is 10,000 Hz and its bit depth is 16 bits per sample.

Written answer2 marks

Show your method for calculating this recording's sound-data size in KB.

Students type their answer here.

Fill in the blanks1 mark
The final size of this recording's uncompressed sound data is Answer 1 KB.
Written answer2 marks

Compare how increasing resolution and increasing colour depth can improve a newly captured bitmap image.

Students type their answer here.

Written answer2 marks

Compare how increasing sample rate and increasing bit depth can improve an analogue sound recording when it is captured.

Students type their answer here.

3. An online exhibition

A school publishes preview photographs online. They need to download quickly and a small quality change is acceptable. The school also keeps a master image for later editing, which must be restored exactly.

Written answer3 marks

Recommend compression for the public preview photographs. Explain a download benefit and a possible drawback.

Students type their answer here.

Written answer2 marks

Recommend compression for the exact master image and justify your choice.

Students type their answer here.

4. Improve one answer

Choose the concept or calculation that was least secure. Return to its teaching worksheet, then improve that existing answer.