Name the attachment
Identify how the subject is joined to the rest — added, multiplied, squared, inside a root.
AQA 8300 · A5 · Formula rearrangement
Rearranging formulae: factor or addend?
The isolation mark. The operation attaching the subject to the rest of the formula determines its inverse, and choosing the wrong inverse loses the method regardless of how tidy the result looks.
Reviewed family · Studara-authored items · No grade-uplift claim
The lost mark
One answer. Several places the method can fail.
Studara does not reduce the response to right or wrong. The reviewed contract checks these states independently.
Apply the inverse
Perform that operation's inverse on both sides, one step at a time.
Isolate the subject
Leave the subject alone on one side, with everything else on the other.
Why it goes wrong
The diagnosis stays uncertainty-safe.
A wrong response can support a specific measured diagnosis. A blind multiple-choice diagnostic records only a possible cause until later working provides stronger evidence.
01
The error
Moving a term across the equals sign when it is a FACTOR rather than an addend — subtracting where dividing was required.
02
Why it survives revision
The rearranged formula looks structurally plausible and there is no number at the end to test it against. Unlike almost every other topic, nothing about the output signals that the method was wrong.
The worked repair
Repair the smallest broken step.
Teaching is not evidence. This one move is the repair; the proof checks begin after it disappears.
Name the operation joining the subject to the rest — added, multiplied, squared — then apply exactly that operation's inverse to both sides.
What happens after the repair
Correction is the start, not the result.
Immediate
Asked again straight away, on a different question
The repair leaves the screen and a new authored item checks the method unassisted. Being taught something is never evidence that it was learned, so this is the first stage that counts at all.
Delayed
Asked again after at least 1 day
A parallel form of the same method, unassisted, with the repair no longer on screen. A retest in the same session does not count.
Transfer
Asked again when the surface changes
The transfer form makes the subject appear twice, so it has to be collected into a single term before it can be isolated at all.
Exam
Asked again under exam conditions
Timed, carrying the mark tariff, in an exam-like response format and aligned to the specification. Any one of those missing and the evidence is refused.
REVIEWED BOUNDARY
This page covers one reviewed family: A5 · Formula rearrangement. Isolate the product, then make one symbol the subject. Other families within the same GCSE Maths topic are outside this reviewed journey, and Studara does not apply the proof label to material that has not been reviewed. No grade-uplift claim is made anywhere on this site.
Straight answers
Before you use this guide.
How do I make a letter the subject of a formula?
Undo whatever is attached to it, in reverse order, doing the same to both sides. The key decision is whether a term is added to the subject or multiplied by it — those need different inverses.
What if the subject appears twice?
Collect both occurrences onto one side and factorise the subject out, then divide by the bracket that remains.
Does Studara guarantee a higher grade?
No. Studara has not run a controlled outcome study and publishes no grade-uplift claim. What has been measured, what is withheld, and the metric that failed its bar are all on the public evidence page.
Turn this method into evidence