Your child stares at a science question and says the thing every parent dreads: “I can’t remember the formula.” The question dies right there. Before you decide the 13 plus exam is a memory contest, give me five minutes. I’m going to teach you, the parent, the trick that rescues that question. Then you’re going to hand it to your child.
The honest version
A forgotten formula isn’t the end of a question. Read this once and you’ll be able to teach your child the way back in.
Your five-minute lesson
Here’s a real question of the kind the 13 plus exam loves. A gravitational field pulls with 10 newtons on every kilogram. An object weighs 5 kilograms. What force does it feel?
There’s a formula for this. Your child has been taught it. Under exam pressure, it’s gone. Now look at what the question handed you instead: newtons per kilogram, and kilograms. Say those out loud. Newtons per kilogram, times kilograms. The kilograms cancel each other out, and what’s left is newtons. Which is exactly what the question asked for.
So the units just told you what to do: multiply. Ten times five, fifty newtons. No formula anywhere. You’ve just done what scientists call dimensional analysis, and you did it at the kitchen table.
“In some questions where you maybe don’t remember the formula, this is called dimensional analysis. It’s to check the units work.”
Gonzalo, 13 plus Science tutor
Hana used to freeze the moment a question needed a formula she couldn’t recall. Her tutor never made her relearn the list. They worked on what the units were telling her, and within a few weeks she was attempting every question instead of skipping the ones that looked scientific. Hana is an invented name and her story mixes a few real students, but the freeze, and the fix, are real.
Now hand it to your child
Next time a formula goes missing, don’t supply it. Ask one question instead: what units did they give you, and what unit does the answer need? Let your child work out what must happen to the numbers so the units come out right. It feels slow the first time. By the third time it’s automatic, and the blank page stops being a dead end.
Two smaller habits travel with it. If the quantity has a unit, the answer needs the unit. Examiners give points for it, and children throw those points away daily. And at the end of every calculation, ask whether the number makes sense. A tiny force on a heavy object should ring an alarm.
Why the 13 plus exam rewards exactly this
The 13 plus exam isn’t looking for the child who memorised the most. Common Entrance at 13 plus is used by more than one hundred independent senior schools, and ISEB has rebuilt it to test problem-solving and reasoning alongside knowledge. The pre-tests used by Eton, Harrow, Winchester and Westminster work the same way. A child who can find a way into a question they don’t recognise is exactly who these papers are built to find.
That’s also why piling on more memorisation is the wrong response when a 13 plus mock disappoints. The child who froze didn’t run out of knowledge. They ran out of ways in. We say more about what the papers demand in our guide to how hard 13 plus Common Entrance really is. The deeper skill is covered in teaching problem solving rather than pattern spotting.
What a tutor adds that this article can’t
The units trick took you five minutes. What takes longer is spotting which way in your child is missing on the other kinds of question. Each subject has its own version of the blank page. Our tutors work to the exact papers your child is sitting. They watch where they give up, then teach the specific check that gets them moving again. You get a short written note after every session, so you can see the habits building rather than taking our word for it.
Find where your child gives up
That moment is where the points are going. One lesson usually finds it.
The tutors who teach this way
Martin
Martin prepares children for private school admissions maths at 7 plus, 11 plus and 13 plus, and teaches Maths and Further Maths to A Level. He has seen more entrance papers than almost anyone, so he knows which habits actually earn points in them.
Louis
Louis teaches 13 plus alongside French, Philosophy and English, and he supports Oxbridge applicants too. He is good with children who go quiet when they are unsure, because he gets them talking through a problem instead of freezing over it.
Ramsay
Ramsay supports school entrance maths through to A Level, with Distinctions in both rounds of the British Mathematical Olympiad and twelve grade 9s at GCSE. He teaches children to reason their way into a question rather than reach for a remembered rule.
Worth reading next
Give your child a way into every question
START WITH A DIAGNOSTIC LESSON
We find where your child stops, then teach the habit that gets them moving again.
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