Redpen marks your practice answers the way your exam board does, shows the exact words that lost the mark, and chooses what you revise next.
Explain why packet switching is used to send data across the internet.
Data is split into packets✓ which can take different routes✓ so it is faster and better.
The mark scheme wants a consequence: if one route is congested or fails, packets are re-routed, so the message still arrives. Say that and the third mark is yours.
Most revision tools give you a library and wish you luck. Redpen makes the calls a good tutor would.
You never pick what to study. Each session looks at what you actually know and picks one topic: usually your weakest, unless it depends on something you haven’t learned yet.
Questions are generated fresh around the facts the mark scheme requires, and checked against real exam wording first. Practising again means a new scenario, not a question you’ve memorised.
Code you write is run against real test cases. Assembly runs on a genuine instruction-set simulator. Nothing is marked on “looks about right”.
Your score rises when you get a topic right and slowly fades if you leave it, so it shows what you know now, not what you once got right.
A wrong answer opens a panel showing exactly what the examiner needed and where your answer fell short. Fix it there, then get a fresh question on the same idea.
Practice gives hints and instant feedback on every question. Mock exams are the opposite on purpose: timed, no hints, nothing marked until you submit the whole paper.
Cambridge gives marks from a mark scheme. The College Board awards points from scoring guidelines. Every Redpen course uses its own exam's rules, and runs your code in the language it's set in. Here's 9618 today, and AP CS A when it launches.
Get a theory answer wrong and this slides out: the exact reasoning the marker used, your wording next to the standard answer, and a box to fix yours right there.
Fix it, and the next question tests the same idea in a new scenario, not the one you just saw.
State two differences between a hub and a switch.
A switch sends data only to the device it is meant for. A switch is faster and more efficient.
A hub broadcasts to all devices; a switch sends only to the destination device. A switch stores and uses MAC addresses; a hub does not.
We launch a syllabus only when every papers is covered, from the official specification and years of past papers.
All 52 topics across AS and A2. Pseudocode run against test cases, assembly on a real CS 9618 instruction-set simulator, and a target grade and exam date for each paper.
Every number below was measured against Redpen's own grading code and syllabus content. None of them are marketing estimates.
Every course has a free audit, a pass for one exam, and a pass for the whole course. No subscription, no card kept on file.
See full pricing →Class rosters, per-topic heatmaps, mock results by paper and one invoice, for any course we cover. Tell us what your department needs and we'll scope it together.
Marking is calibrated against each exam board’s published mark schemes or scoring guidelines. Redpen is independent and not endorsed by any board.
Yes. Pseudocode, assembly, Python and Java answers are executed against test cases, the same way an examiner checks what your program would do.
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No. Passes are one payment for a set time. We don’t keep your card for renewals.