Computer Science, taught properly.
Karachi-based, taught worldwide. The kind of teaching that makes hard ideas genuinely click, so students understand the subject and don't just memorise it. A decade of national and provincial toppers to show for it.
Names, not numbers.
A decade of national and provincial toppers, across every Cambridge level. Not a promise, a track record. Here are some of them, in their own words.
"He makes genuinely complex ideas simple. I trusted him with my own A Levels, and so should you."
Distinction · Top in Sindh & Bal."He teaches the syllabus exceptionally well, but it's the support beyond the classroom that sets him apart."
Distinction · Top in Sindh & Bal."His notes and constant support cleared up every vague idea I had. This award simply wouldn't exist without him."
Distinction · Top in Sindh & Bal."He covers an entire syllabus in months. His notes and topical past papers took me past an A* to a distinction."
Distinction · Top in Sindh & Bal."His teaching makes you master every specification. I still use the problem-solving habits he gave me at work today."
Distinction · Top in Pakistan"He covered every base and made time for each of us individually. The classes were never once boring."
Distinction · Top in Pakistan
Zain Merchant
I've spent over a decade teaching Cambridge Computer Science at Karachi's top colleges, and I founded CS with Zain to put that same teaching within reach of any student, anywhere.
My students don't memorise their way to a grade. They actually understand the subject. That's what has produced national and provincial toppers, year after year, and it's the thinking behind everything I post.
Education
Background
Where I teach
Three courses. One standard.
Full Cambridge Computer Science coverage, taught to examiner expectations. Pick the course you sit.
O Level and IGCSE CS
Foundations done right: pseudocode, trace tables and exam technique that turns understanding into marks across both syllabuses.
AS Level CS
The AS year: information representation, hardware, programming fundamentals and problem-solving, drilled against the mark scheme.
A Level CS (A2)
The second year: advanced theory, algorithms, Python for Paper 4, and the AI and machine-learning content, taught to the depth the examiner rewards.
Built for my classes. Open to you.
The same material my students revise with. Every answer is in real mark-scheme wording, and every trap is a mistake that really loses marks in the exam.
Free to use · No sign-up · Works on a phone
A real card from O Level Paper 1, Data storage.
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01
Flashcards and quizzes
Learn the card, then test yourself on the answers that lose marks, then beat the clock in the Trap Gauntlet.
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02
Paper 4 Python
The A Level 9618 course. Read the notes for a block, then write each step's program and have it checked against the exact output.
ABCDEFGHIJKLMNOPQRBlocks A to C open now, 28 steps. D to R are on the way.
Start at Block A → -
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Where can I apply?
The university guide. Pick your A Level subjects and see which of 31 Computer Science degrees they keep open, in Pakistan and abroad.
Check my subjects →
In development: O Level Paper 2 and AS Paper 2 flashcards. New decks are announced on @cswithzain.
Understand it, then prove it.
Concepts first, always
We build genuine understanding of how computers and algorithms actually work, not memorised answers. The marks follow from that.
Then prove it on paper
Once the idea is solid, students learn to express it the way the examiner rewards: command words, marking points, clear working.
Notes that hold up
Written lecture notes and topical past papers that students return to long after the class ends.
Support beyond class
Individual guidance outside scheduled hours, on the syllabus and on the choices that come after it.
Honest, not hype.
No shortcuts, no inflated promises. Just clear teaching and a record you can check. If a topic is hard, we sit with it until it clicks. The marks are the by-product, not the point.
Try it on a real question →Watch a problem break down.
This is a real O Level question. Most students get the first answer and lose the rest. Step through it the way we teach it, one line at a time.
Numbers ← [3, 8, 8, 2, 8, 5]. Complete a trace table. What does the algorithm output, and what does Count actually measure? [4]
Press Start to walk through the algorithm step by step.
Enrolling now.
Tell me where you are in the course.
Fill in the form or message on WhatsApp. I'll suggest a class time and a plan that fits how much time you have before your exam. There's no payment at this stage.
Register now → WhatsApp us instead →Form takes under a minute · or message us directly.
Before you ask.
Cambridge O Level Computer Science (2210), IGCSE Computer Science (0478), and AS & A Level Computer Science (9618). The full theory and programming content for each, taught to the current syllabus.
Both. Classes run in Karachi and online for students worldwide. Many distinction-holders studied entirely online, including private candidates.
Yes. Several toppers prepared as private candidates with structured notes, topical past papers, and individual guidance throughout.
Lectures, written lecture notes, topical past papers, and focused past-paper sessions in the run-up to exams, plus support outside scheduled class time.
No. The Paper 4 course runs in the browser. Read the notes on a phone; write and check your programs on a laptop.
Fill in the form above, message us on WhatsApp, or send a DM on Instagram. Class timings and fees are sorted out with you on WhatsApp.