I spent 18 years marking the same mistake.

Not the same wrong answer — the same kind of loss. A student who understood the concept perfectly, sitting across from me, unable to explain why their mark said 4 out of 7. I've been the person on the other side of that conversation for most of my career: 18 years teaching IB and IGCSE Computer Science, an examination officer for both CAIE and the IBDP, an electrical and electronic engineer by training before I was ever a teacher. Over 80% of my students leave with a distinction. Several have placed Top in the World in Cambridge IGCSE and A-Level Computer Science. My IBDP students regularly score 6s and 7s.

I'm telling you this first because it's the reason I get to have an opinion about what's broken in how students practise — not because a title needs defending, but because you deserve to know why the person who built this thinks the way they do.

Here's the pattern I couldn't stop seeing.

Two students would sit the same paper. Same topic, same revision time, same effort by any measure I could see. One would climb. One would plateau — and stay there, mark after mark, no matter how much more they practised.

For years I assumed it was a knowledge problem, because that's the only lever a worksheet gives you: more questions, more repetition, more of the same medicine. But when I actually sat down and read the plateaued student's scripts line by line — not just the score, the reasoning — the real story was almost never “they don't know this.” It was one of three much narrower things: they'd genuinely misunderstood a concept, they'd understood it but the question's wording had thrown them, or they knew the content cold and lost the marks anyway because they answered in the wrong genre for what the command word actually asked.

Three different problems. One prescription — “revise and try again” — that only ever fixed the first one.

I can't tell you which students, for reasons that should be obvious to anyone who's worked in a school — but I can tell you the shape of it, because I've watched it happen more than once. A student starting Year 9 at a D, given nothing but the same worksheet everyone else got, finishing the IGCSE with an A once I started diagnosing instead of just re-assigning. An IB student sitting at a 3, climbing to a 6 — sometimes a 7 — on the back of feedback that told them what kind of mistake they were making, every time, not just that a mistake had been made. That gap between a 3 and a 6 isn't more effort. It's the same effort, finally pointed at the right thing.

That's the gap ExamEdge exists to close. Not “more practice” — a system that reads a wrong answer the way I learned to read one after 18 years of doing it by hand, and tells the student which of the three problems they actually have, before assigning them anything.

I still mark like a teacher, not a platform.

I didn't set out to build software. I built ExamEdge because I couldn't do for every class what I could do for one script at a time — and I teach Year 9 through Year 12, several classes deep, on top of marking, setting papers, and running the events a school actually runs on. There was never enough of me to give every student the kind of feedback that took that Year 9 D to an A, every time, for everyone. The app is the part of the job I couldn't scale by hand.

I'm still building it in whatever time I can find between the rest of that job — it improves because I'm still in a classroom, still marking, still noticing what a generic tool would miss. That's deliberate, not a gap I'm waiting to close: the day this stops being shaped by someone who's still teaching is the day it starts drifting from what actually helps in a real classroom.

It also means I hold this to a standard most ed-tech doesn't have to answer to. If a student uses a hint or a mark scheme mid-attempt, that attempt gets flagged — it never counts as clean mastery, because I've seen what happens when a school trusts data that quietly isn't real. I'd rather show you an honest gap than a flattering dashboard.

Right now this is Computer Science, IB and IGCSE. But the problem I kept seeing — a mark with no explanation, three different failures treated as one — isn't unique to my subject. I'd like to bring the same approach to other subjects over time, for the same reason I built the first version: there are teachers marking exactly what I used to mark, with exactly as little spare time as I had.

If you're a teacher, I built the tool I wished I'd had for every class I couldn't give individual attention to fast enough. If you're a student, I built it because you deserve to know why, not just whether. Either way — you're not talking to a company. You're talking to the person who marked the scripts.

Ren Lee
Founder, ExamEdge. Senior STEM Educator, CAIE & IBDP Examination Officer, BEng (Hons) Electrical & Electronic Engineering (NTU), PGDE (NIE, NTU).