THE RUBEN THEOREM GCSE Maths. Learn it. Prove it.

For parents of Year 9 to 11 GCSE maths students, Foundation and Higher

Your child can use the same AI system that took ten-year-old Ruben from a grade 6 to a grade 9.

Whatever grade your child is on, a topic they have never understood is worked through with them, then they do one alone. Three independent AI markers mark the handwritten work against their exam board’s mark scheme, tracing each lost mark to its cause. Then they win it back on questions that look alike but need different methods, as the exam does.

Apply for a founding place See how the formula works

100 founding places this term. Takes one minute, no payment today.

What your child is up against, and what we do about it

Six things parents and students told us when we asked what goes wrong.

“I know how to do it. I just keep losing marks.”

Our system grades every paper and practice question your child does, against their exam board’s mark scheme. The result comes back in under 10 minutes, with each lost mark traced to its cause. For a child who says this, it’s usually a slip, a misread question, a miscopied answer, or stopping one step early.

“I get a question I’ve never seen before and I don’t know where to start.”

Our system trains your child to apply what they know to questions they haven’t seen before. It sets fresh questions that mix topics without naming them, so your child practises spotting which method a question needs.

“It tells me I’m wrong. It never tells me why.”

Our system traces each mark back to the point on the mark scheme that earned or lost it, so your child can follow our step-by-step working as well as their own.

“Group classes move at the group’s pace. My child gets left behind.”

There’s no class here and nobody to keep up with. Almost everything our system sets comes from your child’s own work and their own mistakes, so the whole thing is built around them.

“They didn’t understand the explanation, and nobody gave them another one.”

If they don’t get it, our system explains it again a different way, and keeps trying different ways.

“I’ve no idea whether she’s actually making progress.”

Our system emails you every week with what they practised, which marks they got back, and an updated likely grade. That likely grade gets more accurate with every paper, and the email names the specific mistakes that keep costing them.

The Ruben Formula

Every lesson and every question goes round the same loop.

This is the Ruben Formula, the four stages inside our system. Your child starts wherever makes sense for them. A topic they have never understood starts at Teach. Maths they know but keep losing marks on starts at Practise, or at Mark with a paper they have already sat. Each mistake then goes round the loop until your child is winning those marks back.

  • Teach A topic your child has never understood is worked through with them, step by step, then they do one alone. If an explanation doesn’t work, it tries another until it makes sense.
  • Practise Your child always attempts first, on screen in the app. Questions that look alike need different methods, so they have to choose. The app marks each answer instantly and shows how to win the mark back.
  • Mark On paper, because that is how the exam is marked. Your child answers a past paper, or a few questions, by hand and photographs it. Three AI markers award method marks against their exam board’s mark scheme.
  • Fix and prove Each lost mark is traced to one of five causes and checked against earlier work for a pattern. The fix is taught, then proved on questions your child has not seen.

A mistake isn’t fixed when it has been explained. It’s fixed when your child wins those marks back and keeps winning them.

No video can tell you whether your child could have done it alone. Their handwriting can.

We welcome GCSE maths students on Edexcel, AQA, OCR and IGCSE.

What the feedback looks like

A typical revision app tells your child which topic to revise. Our system tells them what they did, on which line, and what to practise instead. These four are short extracts from reports that cover every mark.

Typical feedback

Weak on standard form. Twenty practice questions.

Our feedback

The student knows how to write numbers in standard form, and can add them when both numbers have the same power of ten. This mark was lost because the powers were different: 5.7 × 10² + 9.8 × 10³. To add them, the second number had to be rewritten as 98 × 10², and the student wrote 0.98 × 10² instead. Moving the decimal point one place to the left means the power should go up by one, and it was taken down by one. The practice is six additions, getting harder as they go, with that rewriting step done every time, so this mark isn’t lost again. In two of the six the powers already match, so the right move is to add them as they stand.

Typical feedback

Practise algebraic proof.

Our feedback

Both proofs were set up the right way and the working was correct almost to the end. Both marks were lost in the last two lines. In one, a squared term was copied down without its square. In the other, a plus became a minus when the brackets were removed, so the final answer came out negative when it should have been positive. On this paper, four of the eight marks lost were on questions where the method was right. The practice is five proofs, with one rule: check the final line against the line above before writing the conclusion. That way the slip is caught before it costs the mark. One of the five is a disproof, so your child has to spot that a counterexample is what’s wanted.

Typical feedback

Revise transformations.

Our feedback

The student found the right centre and the right angle for the rotation. The mark was lost on the direction. The shape started above and to the right of the centre and finished above and to the left, which is an anticlockwise turn. The student wrote clockwise, which would have sent the shape below and to the right. The practice is four rotations, two in each direction, with a quick sketch of where the shape lands before the direction is written, so the direction is right next time. A reflection and an enlargement are mixed in, because the first job in the exam is working out which transformation you have been given.

Typical feedback

Revise proportion.

Our feedback

The student handles direct proportion well. This question said one quantity was inversely proportional to the square of another. The student wrote the formula as if it were directly proportional, and left out the inverse. When a question combines two ideas, inverse and squared, one of them tends to get dropped. The practice is six questions alternating between direct and inverse, with the formula written out before any numbers go in, so the inverse isn’t dropped again. Two of them look inverse and turn out to be direct, which is the trap a real paper sets.

The practice and the new questions are built directly from the mistake, and get harder step by step. That’s how your child learns to get the marks on a question they’ve never seen before.

Why it is built this way

What we’re betting on, and what the evidence shows.

Mixing beats one topic at a time.In a randomised trial in real classrooms, pupils who practised mixed maths problems scored 61% on a test a month later. Pupils who practised the same problems grouped by topic scored 38%. This is one of the findings our system is built around.

Being shown feels like learning.Students who watch a smooth worked solution consistently overestimate how much of it they have kept. The feeling of understanding is not the same as being able to do it alone. It is why the real exam often feels harder than they expected.

Getting it wrong first helps, once they know the topic.Attempting, being wrong, then being corrected sticks better than being shown the answer up front, and errors made confidently are corrected most strongly. Working out which method a question needs is a separate skill from carrying it out, so your child does that part themselves too. Before they know the topic the opposite holds, which is why a topic your child has never understood is worked through with them.

None of these studies tested our product. They are the reasons we built it this way, not evidence that it works for your child. That evidence comes from your child’s own marks, and you see those every week.

Ruben’s story

How Ruben went from a grade 6 to a grade 9 in three months.

Ruben, aged ten, smiling and holding his GCSE maths result slip showing 224 out of 240, grade 9.
Ruben, ten, with the result: 224 out of 240.

Ruben’s first timed GCSE paper came out at grade 6. We used the system we’d built to simplify concepts, expose gaps, analyse lost marks and fix recurring mistakes. When he sat the real exam, he scored 224 out of 240. Ruben was ten, which is unusual. The mistakes he made are not; they’re the ones examiners see in GCSE maths papers every summer.

Marking his past papers myself took hours, and doing more of them didn’t fix what he kept getting wrong. He needed a system that found the pattern across everything he’d done, and explained it until it made sense. Then it set him new questions he’d never seen, until he won those marks back consistently.

Mani, Ruben’s dad and co-founder of therubentheorem.com
(Ruben is the other co-founder!)

Founding places

100 places. Then January.

Click below to apply for a founding place. When the 100 are gone, the next intake is January. Applying is not the same as signing up. You get my written answer on whether this fits your child.

Your child can use the same AI system that took Ruben up three grades in three months.

A topic your child has never understood gets taught, with the explanation changing until it lands. Maths they know but still lose marks on gets graded by three AI markers against their exam board’s mark scheme, in under 10 minutes. Every lost mark is traced to its cause, and when that cause returns they get new questions built on it. Applying is free and takes a minute.

  • £49.99 a month, and your price never rises while you stay. From January new families pay £60 a month. You can cancel any time.

Nothing is charged today, and nothing is charged until you have read my reply and said yes. I read every application myself and reply within two working days. If you have a question, or someone else needs to see this first, ask in the application and my reply will answer it.

Questions parents typically ask

“Does it work?”
Ruben scored 224 out of 240 in the real exam. On Higher tier, this system is built to help students achieve up to a three-grade jump, although results will differ from child to child. We’ll show you the marks every week, and you can judge for yourself. This is a founding group, so there’s no grade guarantee yet. From January we publish the group’s results, measured on real papers, with families’ permission and no names, and the guarantee comes after that.
“Will it work for my child?”
It’s for Year 9 to 11 students on Foundation or Higher. That runs from a child who says they’re not a maths person to one on an 8 aiming for a 9. Nobody has to start with a timed paper. A child who finds exams stressful can start by learning a topic instead. If they do sit one, a low score is useful, because it shows us where to start. In Year 9 much of the course has not been taught yet, so blanks are expected. Nobody sees it except you and us. Your answers on the application help us say whether it’s a good fit before you pay anything.
“Is my child being taught by AI?”
Yes. The teaching, the marking and the questions are all AI, and we would rather say that plainly than have you find out later. It is not a general chatbot. It works to one thing, your child’s exam board’s mark scheme, including its rules on method marks and follow-through. The papers are the board’s own past papers. A person steps in twice. Where the three markers disagree, an experienced maths teacher settles it. If you ever think a mark is wrong, tell us and a person checks it. Being AI is the reason it can do this at all. No tutor can mark every paper in under 10 minutes. None can hold every mistake your child has made since September, or explain one topic a different way each time without tiring.
“What if my child won’t do it?”
Most won’t, at first. That is why nothing here starts with a blank page. A topic they have never understood is worked through with them before they try one. When a mark is lost, we name what went wrong, not the child. Sessions are short and your child chooses when. We suggest two to three hours a week. The weekly email shows you what they did, so you are not the one chasing.
“Why doesn’t it just show my child how it’s done?”
For a topic they have never met, it does, and then they immediately do one themselves. After that, watching stops working. A child who watches a clean solution feels like they have learned it and then loses the same marks in the exam. Doing one alone is the only thing that proves it stuck.
“What are founding families getting first?”
One thing is not built yet, and founding families get it first at no extra cost. Each question will ask which method it needs before your child solves it. That tells us whether a lost mark came from choosing the wrong method or from a slip in the working. Those are two different problems with two different fixes.
“Do we still need a tutor?”
Some families keep both, and some stop. A tutor sees the hour your child is with them. We see every question your child has answered, which is where a pattern shows up, and every paper comes back marked against their exam board’s mark scheme in under 10 minutes. If your child needs someone in the room with them, keep the tutor.
“Which exam boards do you cover?”
Edexcel, AQA, OCR and IGCSE. We grade every paper and practice question against that exam board’s mark scheme. Your child is marked the way their exam will be. If you’re not sure which board they’re on, it’s on their mock paper, and “not sure” is a fine answer on the application.
“Is Foundation tier included?”
Yes, Foundation and Higher are both included. Foundation papers are marked against the Foundation mark scheme for your child’s exam board.
“Can a computer mark handwritten maths?”
Three independent AI markers grade each piece of work at the same time. Independent means none of them can see what the others have given. They then compare their marks and agree a result. Each one marks against the mark scheme for your child’s exam board, including its rules on method marks and follow-through. In under 10 minutes your child has the result, where each mark went, and what to do about it. Each mark shows the scheme point behind it, so you can check our working. Where the three disagree, they flag it rather than guess, and an experienced maths teacher settles those afterwards. You see what was disputed and the ruling. And if you ever think a mark is wrong, tell us and a person will check it.
“What do we get, and where do the papers and questions come from?”
The daily question sets come from us, written in exam style to your child’s exam board’s mark scheme. They are chosen from their own mistakes. Papers and practice questions are marked the same way, so a child who works through questions rather than whole papers gets the same feedback. Week one can start with a timed paper, so there’s something to work from, or with a topic your child wants to fix. The timed papers are official past papers, free to download from the exam board’s website; we send the link and say which one to sit. You’ll need a printer for the papers and a phone to photograph the work.
“How do you spot a mistake that keeps coming back?”
Our system keeps a record of every mark your child has lost, across every paper and practice question, each with its cause. The causes are didn’t know it, knew it and slipped, answered a different question, copied their own working wrongly, and stopped one step early. It compares each new mistake with every old one, even from many papers ago and even when the questions look different. The pattern then decides what to teach or practise next. That is the part a person marking week by week cannot hold in their head. You can open the record any time, and the weekly email quotes from it.
“Is their information safe?”
You hold the account; your child has a profile inside it. We keep the minimum, delete it on request, and their work is never used to train AI. Photographs of work are deleted within 30 days of grading unless you choose to keep them.
“What does it cost, and when do I pay?”
£49.99 a month, and your price never rises while you stay. Nothing to pay when you apply, and nothing is charged until you have read my reply and said yes. From January new families pay £60 a month. It’s monthly. Cancel from your account whenever you like.
“How much time does it take?”
As much or as little as you like. We suggest two to three hours a week, and your child chooses how to spread it. A full timed paper is not required, so they can work through a set of exam questions instead. Whatever they do comes back marked, and the weekly email shows you what they did.
“My child won’t stick at it.”
Most revision apps are abandoned within a few weeks, so this is built to be easy to keep going. The first session is short and ends with your child getting something right. Reminders come once a day, at a time your child chooses, and they stop if they’re ignored. Your child builds a run of days in a row, with a free day off built in, so missing one day doesn’t spoil a good week. And your weekly email tells you in the first fortnight whether it’s working.

100 places. When they’re gone, the next intake is January.