GCSE Computer Science
Mae disgrifiadau'r TGAU yn Saesneg yn unig, gan eu bod wedi eu cymryd o fanyleb Saesneg CBAC.
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.
- Addysgu gyntaf
- Medi 2025
- Faint o waith llythrennedd
- Canolig
- Faint o waith rhifedd
- Uchel
- Manyleb
- Agor manyleb CBAC (PDF)
Sut mae'r TGAU hwn yn cael ei asesu
- 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
Sgiliau sy'n defnyddio Rhesymu rhesymegol
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Converting between denary, binary and hexadecimal
Learners convert between denary, binary and hexadecimal, perform binary addition, use arithmetic shifts and explain overflow and underflow. All of this rests on secure place value and powers of 2.
Rhifedd: Y system rif, Cyfrifiad, Perthnasoedd yn y system rif, Dealltwriaeth gysyniadol, Rhuglder, Rhesymu rhesymegol
Paratoi disgyblion
- Blwyddyn 7
- Pupils use binary place-value cards from 128 down to 1 to make their age and house number, write each as 8-bit binary and check by adding the place values.
- Blwyddyn 8
- Pupils add two 8-bit binary numbers in columns, convert the answer to denary to check it, and explain in one sentence what happens when a ninth bit is needed.
- Blwyddyn 9
- Pupils convert web colour codes such as FF8800 from hexadecimal to denary and binary, and show that a left shift of one place doubles a binary number.
Dangos geiriad y fanyleb a datganiadau'r Fframwaith Llythrennedd a Rhifedd
Ble mae yn y fanyleb: Unit 1, Section 1.2.1, page 13
“convert between, denary, binary and hexadecimal counting systems”
Cam cynnydd 3
Rwy'n gallu darllen ac ysgrifennu rhifau hyd at 1 filiwn a rhifau hyd at 3 lle degol.
Rwy'n gallu adio a thynnu rhifau gan ddefnyddio rhifau cyfan a degolion.
Rwy'n gallu defnyddio amrywiaeth o strategaethau i wirio cyfrifiadau gan gynnwys defnyddio gweithrediadau gwrthdro, cyfrifiadau cywerth a rheolau rhanadwyedd.
Cam cynnydd 4
Rwy'n gallu defnyddio pwerau a deall pwysigrwydd pwerau 10.
Rwy'n gallu cynrychioli cysyniad mewn ffyrdd gwahanol, gan lifo rhwng cynrychioliadau gwahanol gan gynnwys rhai llafar, diriaethol, gweledol, digidol a haniaethol.
Rwy'n gallu defnyddio'r pedwar gweithrediad a'r cysylltiadau rhyngddyn nhw, e.e. cymhwyso swm rhannu fel gwrthdro i swm lluosi.
Cam cynnydd 5
Rwy'n gallu cynrychioli cysyniad mewn ffyrdd gwahanol, gan lifo rhwng cynrychioliadau gwahanol gan gynnwys rhai llafar, diriaethol, gweledol, digidol a haniaethol.
Rwy'n gallu defnyddio ffeithiau a thechnegau cadarn, cofiadwy a defnyddiadwy er mwyn cymhwyso'r dulliau mwyaf effeithlon.
Rwy'n gallu dilysu a phrofi canlyniadau a datrysiadau.
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Compression ratios and file size reduction
Learners calculate compression ratios and the reduction in file size after lossy or lossless compression, and judge whether the saving is worth the loss of quality.
Rhifedd: Cyfrifiad, Perthnasoedd yn y system rif, Dealltwriaeth gysyniadol, Rhesymu rhesymegol
Paratoi disgyblion
- Blwyddyn 7
- Pupils run-length encode rows of their pixel art, for example 5 white then 3 black, and count how many characters they save compared with listing every pixel.
- Blwyddyn 8
- Pupils zip a folder of text files, record the size before and after, and write the saving as a ratio in its simplest form.
- Blwyddyn 9
- Pupils save one photo as PNG and at three JPEG quality settings, calculate the percentage reduction for each and explain which methods are lossy.
Dangos geiriad y fanyleb a datganiadau'r Fframwaith Llythrennedd a Rhifedd
Ble mae yn y fanyleb: Unit 1, Section 1.2.1, page 14
“calculation of compression ratios and the reduction in file sizes following compression.”
Cam cynnydd 3
Rwy'n gallu defnyddio cymhareb a chyfran i gyfrifo meintiau.
Rwy'n gallu cyfrifo canran, ffracsiwn a degolyn o unrhyw faint gyda chyfrifiannell lle y bo'n briodol.
Rwy'n gallu defnyddio cywerth ffracsiynau, degolion a chanrannau er mwyn cymharu cyfrannau.
Cam cynnydd 4
Rwy'n gallu mynegi un maint fel canran maint arall.
Rwy'n gallu cyfrifo cynnydd neu ostyngiad canrannol.
Rwy'n gallu defnyddio cywerth ffracsiynau, degolion a chanrannau i ddewis yr un mwyaf priodol ar gyfer cyfrifiad.
Cam cynnydd 5
Rwy'n gallu defnyddio lluosyddion fel dull effeithlon wrth weithio gyda chanrannau, e.e. lluosi ag 1.2 i gynyddu swm 20%.
Rwy'n gallu dehongli atebion o fewn cyd-destun y broblem ac ystyried a yw atebion, gan gynnwys dangosyddion cyfrifiannell, analog a digidol, yn synhwyrol.
Rwy'n gallu esbonio canlyniadau a gweithdrefnau yn fanwl gan ddefnyddio iaith fathemategol briodol.
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Logical operators, truth tables and computing operators
Learners use AND, OR, NOT and XOR in truth tables to solve problems, and apply the relational operators and integer division (DIV and MOD) set out in Appendix B when tracing and writing algorithms.
Rhifedd: Rhesymu rhesymegol, Cyfathrebu â symbolau, Cyfrifiad
Paratoi disgyblion
- Blwyddyn 7
- Pupils complete AND and OR truth tables for a burglar alarm that sounds only when it is switched on and a door is open, then test it with switch cards.
- Blwyddyn 8
- Pupils use DIV and MOD to turn a number of seconds into minutes and seconds for a Scratch quiz timer, checking three answers by hand.
- Blwyddyn 9
- Pupils write conditions using >=, <= and <> for a cinema ticket price program and complete a truth table showing which ages each condition accepts.
Dangos geiriad y fanyleb a datganiadau'r Fframwaith Llythrennedd a Rhifedd
Ble mae yn y fanyleb: Unit 1, Section 1.6.1, page 19; Appendix B, pages 34 to 35
“the use of logical operators in truth tables to solve problems”
Cam cynnydd 3
Rwy'n gallu cyfiawnhau fy ngweithdrefnau a'm rhagfynegiadau.
Rwy'n gallu defnyddio nodiant, symbolau ac unedau mesur priodol.
Rwy'n gallu defnyddio strategaethau ymenyddol i gofio tablau lluosi hyd at 10 x 10 a'u defnyddio i ddatrys problemau rhannu.
Cam cynnydd 4
Rwy'n gallu cyfiawnhau fy ngweithdrefnau, fy rhagfynegiadau a'm dyfaliadau.
Rwy'n gallu defnyddio nodiant, symbolau ac unedau mesur priodol, gan gynnwys mesurau cyfansawdd.
Rwy'n gallu defnyddio'r pedwar gweithrediad a'r cysylltiadau rhyngddyn nhw, e.e. cymhwyso swm rhannu fel gwrthdro i swm lluosi.
Cam cynnydd 5
Rwy'n gallu llunio a datblygu dadl fathemategol.
Rwy'n gallu defnyddio nodiant, symbolau ac unedau mesur priodol, gan gynnwys mesurau cyfansawdd.
Rwy'n gallu esbonio canlyniadau a gweithdrefnau yn fanwl gan ddefnyddio iaith fathemategol briodol.
Da gwybod
- No marks are set aside for spelling, punctuation and grammar. The assessment objectives on page 28 cover only knowledge (AO1), application (AO2) and analysis (AO3), so accuracy of language is not separately credited.
- Both units are answered on screen, page 5: Unit 1 is a "Digital examination: 1 hour 30 minutes" and Unit 2 is an "On-screen examination based on a pre-released brief: 2 hours". Pupils need to type extended answers and calculations.
- The specification does not say whether a calculator is allowed in either unit, so centres should check the WJEC instructions for each series. Pupils should be able to do binary, hexadecimal and storage calculations by hand.
- No notes are allowed into the Unit 2 examination, page 28: "learners are not permitted to take any prompts or notes into the examination." A clean copy of the pre-release is provided.
- Unit 1 mixes question types, page 5: "Questions requiring objective responses, short and extended answers."
- Storage units use 1,024, not 1,000, page 13: "kilobyte (i.e. 1,024 bytes)". Pupils who learn 1,000 in Science or Mathematics need the difference made explicit.
- Appendix B, pages 34 to 36, fixes the operators and pseudocode conventions used in questions: "Logical operators AND OR NOT XOR will be in upper case." DIV and MOD are defined with worked examples such as "11 MOD 2 = 1".
- Appendix A, page 32, marks the numeracy strands for geometry and measurement and for statistics and probability as N/A for both units, so there is no graphing or statistics demand.
Cysylltiadau â TGAU eraill
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.
Ffynhonnell: WJEC GCSE Computer Science specification, teaching from 2025, for award from 2027, Version 3, September 2025.