Flashcards and quizzes
Learn each topic with mark-scheme answers. Then try the Trap Gauntlet: 15 seconds a question.
Open →CS with ZainO Level · IGCSE · AS · A Level
Computer Science classes with a teacher students trust.
Online and in Karachi, for O Level, IGCSE, AS and A Level.
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CS with ZainYour practice
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Zain MerchantTop 10 in PakistanCambridge Dedicated Teacher Awards 2026
Top 90 worldwide, from 12,000+ nominations · ICSC Teacher of the Year 2025 · 950+ students every year
Toppers since 2018 →Top 10 in Pakistan and top 90 worldwide · Cambridge Dedicated Teacher Awards 2026 · from 12,000+ nominations
ICSC Teacher of the Year 2025 · International Computer Science Competition
For students
Try today's puzzle.
Three short programs. Say what each one outputs. The puzzle is the same for everyone today, and it changes at midnight, Pakistan time.
Today's puzzleCS with Zain Daily
Three short programs. Say what each one outputs.
Answers checked with the Pseudocode TracerReport a problem
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Your level
Flashcards and quizzes
AS Paper 1 cards with mark-scheme answers, and the Trap Gauntlet.
Open →Paper 1 notes and topicals
Notes for chapters 1 to 8, and past-paper questions with mark schemes.
Open →Paper 3 notes and topicals
Notes and past-paper questions with mark schemes.
Open →Live Wire
Help Saima wire an apartment block with logic gates. Build circuits and complete truth tables.
Play →Bit Garden
Help Hina run a rooftop greenhouse with 8-bit registers. Binary, hex, bit masks and floating point.
Play →Red Planet
Program a rover on Mars with Cambridge pseudocode. Dr Amna guides each mission.
Play →The Records Room
Help Ms Rubina solve cases at a school with SQL. Draw E-R diagrams in the E-R Lab.
Play →The Sorting Depot
Program Bolt the robot with real Cambridge assembly instructions.
Play →Pseudocode Tracer
Write Cambridge pseudocode and run it. Watch the trace table fill in, line by line.
Open →Paper 4 Python
Notes for each block. Write Python in the browser and check it against the exact output.
Open →Flashcards and quizzes
A Level Paper 3 cards with mark-scheme answers, and the Trap Gauntlet.
Open →University guide
Pick your A Level subjects. See which Computer Science degrees they keep open.
Open →Results
Toppers since 2018.
Six students who came top in Pakistan or in Sindh and Balochistan. Each one is named, with the year and the result.
Yousuf KhatriA Level 2025 · Distinction, Top in Sindh & Balochistan“He makes genuinely complex ideas simple. I trusted him with my own A Levels, and so should you.”
Bassam AhmedA Level 2022 · Distinction, Top in Sindh & Balochistan“He teaches the syllabus exceptionally well, but it's the support beyond the classroom that sets him apart.”
Nabiha FatimaA Level 2022 · Distinction, Top in Sindh & Balochistan“His notes and constant support cleared up every vague idea I had. This award simply wouldn't exist without him.”
Muhammad AhmedO Level 2021 · Distinction, Top in Sindh & Balochistan“He covers an entire syllabus in months. His notes and topical past papers took me past an A* to a distinction.”
Abdul Ali KhanA Level 2019 · Distinction, Top in Pakistan“His teaching makes you master every specification. I still use the problem-solving habits he gave me at work today.”
Huzefa TahirA Level 2018 · Distinction, Top in Pakistan“He covered every base and made time for each of us individually. The classes were never once boring.”
Who teaches you
Meet your teacher.
I am Zain Merchant. I teach Computer Science online and in Karachi.
- MS Computer Science from IBA. BS Computer Science from FAST.
- I worked as a programmer at Microsoft from 2013 to 2015.
- I have taught Cambridge Computer Science since 2016, and trained 1.2k+ teachers.
- I teach students in Pakistan and abroad, in English and Urdu.
Classes
Ask about available seats.
- Online, or in person in Karachi.
- Classes in Karachi have their own times. The team shares them on WhatsApp.
- Includes lectures, notes, topical past papers and pre-exam sessions.
- No payment to register. Fees are shared on WhatsApp.
Ask on WhatsApp. The message is already written.
Online class timings, live on Zoom
- O Level and IGCSE2210 · 0478Tue and Thu5:45 to 7:00 pm
- AS Level9618Fri and Sat5:00 to 6:00 pm
- A Level (A2)9618Fri and Sat6:00 to 7:00 pm
Pakistan time (PKT).
Or use the registration form. It takes about a minute.
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