LNF Cymru Literacy and numeracy for Wales

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GCSE Computer Science

Numeracy is heavy and specific: learners convert between denary, binary and hexadecimal, add in binary, work with base 2 storage units, calculate image, sound and compressed file sizes and routing costs, and reason with truth tables and DIV and MOD. Literacy centres on close reading of the Unit 2 scenario and requirements, precise technical vocabulary, short and extended judgement answers in Unit 1, and code annotation and test commentaries. The single biggest thing Key Stage 3 should build is fluent place value in base 2 and base 16, so that storage and file size calculations become routine.

Awarding body
WJEC
Level
Level 1 and Level 2
First taught
September 2025
Amount of literacy work
Medium
Amount of numeracy work
High
Specification
Open the specification
How this qualification is assessed
  • Unit 1: Understanding Computer Science: Digital examination 1 hour 30 minutes, 50%, 80 marks
  • Unit 2: Computer Programming: On-screen examination based on a pre-released brief, 2 hours, 50%, 80 marks, set and marked by WJEC

Skills that use Strategic competence

  1. Calculating file sizes for images and sound

    Assessed: In the exam

    Learners calculate the storage needed for graphics from dimensions and colour depth, and for sound from sampling rate, bit depth and length, then convert the result into suitable units.

    Numeracy: Shape and space, Calculation, Strategic competence, Measurement, Communicating with symbols

    Getting pupils ready

    Year 7
    Pupils draw an 8 by 8 pixel icon on squared paper using four colours, find the number of pixels as an area and work out that each pixel needs 2 bits.
    Year 8
    Pupils use width times height times colour depth to calculate the file size of their pixel art in bits and bytes, then predict what doubling the colour depth does.
    Year 9
    Pupils record a 10 second sound clip in Audacity, calculate its size from sample rate, bit depth and length, and compare their answer with the saved file size.
    Show the specification wording and the LNF statements

    Where it is in the specification: Unit 1, Section 1.2.1, page 13

    “how to calculate the storage requirements for graphics using different dimensions, bit depths and colour depths.”
    Progression step 3

    • I can find areas by counting squares, progressing to calculating the area of squares and rectangles using formulae.

    • I can multiply 2- and 3-digit numbers by a 2-digit number.

    • I can prioritise and organise the relevant steps needed to complete the task or reach a solution.

    Progression step 4

    • I can demonstrate an understanding of the relationship between a formula representing a measurement and the units used.

    • I can use the order of operations including brackets and powers.

    • I can prioritise and organise the relevant steps needed to complete the task or reach a solution.

    Progression step 5

    • I can recognise, model and apply the underlying mathematical structures and ideas within problems, in order to formulate and solve them.

    • I can refine methods of recording calculations.

    • I can understand and use a variety of compound measures.

  2. Calculating the cost of routing data

    Assessed: In the exam

    Learners calculate the cost of routing data across a network by adding link costs along possible routes and comparing the totals to find the cheapest.

    Numeracy: Strategic competence, Calculation, Fluency

    Getting pupils ready

    Year 7
    Pupils find the cheapest route for a message between rooms on a school map where each corridor has a cost, adding the totals for three routes.
    Year 8
    Pupils list every route between two routers on a six-node network diagram with decimal link costs, add each total and circle the lowest.
    Year 9
    Pupils recalculate the cheapest route when one link on a network diagram fails and write a sentence justifying their new choice with the totals.
    Show the specification wording and the LNF statements

    Where it is in the specification: Unit 1, Section 1.3.1, page 15

    “cost calculation of routing data on a network.”
    Progression step 3

    • I can select, trial and evaluate a variety of possible approaches and break problems into a series of tasks.

    • I can add and subtract numbers using whole numbers and decimals.

    • I can select and apply appropriate checking strategies.

    Progression step 4

    • I can select, trial and evaluate a variety of possible approaches and break complex problems into a series of tasks.

    • I can use efficient written methods to add and subtract numbers and decimals of any size, including a mixture of large and small numbers with differing numbers of decimal places.

    • I can select and apply appropriate checking strategies.

    Progression step 5

    • I can select, trial and evaluate a variety of possible approaches and break complex problems into a series of tasks.

    • I can prioritise and organise the relevant steps needed to complete the task or reach a solution.

    • I can select and apply appropriate checking strategies.

Good to know

Links with other qualifications

Place value, powers, ratio and percentage reduction are taught in Mathematics, so agreeing shared language (for example 'column value' and 'simplest form') with the Mathematics department in Years 7 to 9 will help pupils transfer these skills to binary and file size work.

Source: WJEC GCSE Computer Science specification, teaching from 2025, for award from 2027, Version 3, September 2025.