Every wrong answer has a reason behind it. These pages name 471 of them across 104 topics: what each one looks like in your child's work, why it happens, and the one thing that puts it right. Free to read, no account needed.
A pattern used instead of a real guess. Marks given up that were still available.
6 mistakes explainedAn alternating pattern applied to the wrong terms. One strand left where it was.
6 mistakes explainedA future value given where the present was asked for. One step too many taken.
7 mistakes explainedA growing gap treated as fixed. A symbol repeated in a row that uses each once.
7 mistakes explainedA rule read backwards. An answer that breaks a given clue.
5 mistakes explainedAhead and behind the wrong way round. The answer given in the wrong unit.
4 mistakes explainedFaces that touch mistaken for faces opposite. Faces, edges and vertices mixed up.
3 mistakes explainedMinutes treated as decimals. The hours counted wrongly.
9 mistakes explainedA letter run that is not a real word. A linked word instead of the matching relation.
Movement along the number line in the wrong direction. Ordering negatives by the size of the digits.
5 mistakes explainedAn angle given where the number of sides was wanted. Interior and exterior angles swapped.
5 mistakes explainedSubtracted from 360 instead of 180. Subtracted from 90 instead of 180.
4 mistakes explainedArea given where perimeter was asked for. One side used for both dimensions.
3 mistakes explainedDivided by the number of rows instead of the number of items. The frequency column ignored.
4 mistakes explainedCircumference calculated where area was wanted. The diameter used where the radius belongs.
3 mistakes explainedCollecting a subtracted term as if it were added. Collecting terms that are not alike.
5 mistakes explainedAn overlap counted twice. More events multiplied than the question has.
4 mistakes explainedThe corners of a surrounding path left out. The cut-out piece added on.
3 mistakes explainedThe decimal digits copied straight into a fraction. The longer decimal is the bigger one.
4 mistakes explainedA transformation that preserves size thought to change it. Divided by the scale factor.
3 mistakes explainedA common factor left inside a bracket. Finding numbers that multiply but do not add.
3 mistakes explainedA different fraction of the amount found. Finding one part and stopping.
3 mistakes explainedA coordinate given as the gradient. The change in y given without dividing.
5 mistakes explainedCertainty claimed from a test. The critical region put in the wrong tail.
10 mistakes explainedA constant term not integrated. Divided by the original power rather than the new one.
5 mistakes explainedCounting the position wrong. Doing the operations in the order they are written.
3 mistakes explainedThe components added to give the magnitude. The sides added without squaring.
5 mistakes explainedParallel judged by the constant. The perpendicular gradient used for a parallel line.
3 mistakes explainedA sign change treated as a scalar multiple. Only one component checked for the multiple.
4 mistakes explainedA repeated change applied only once. Adding the percentages instead of multiplying.
3 mistakes explainedComparing a decimal, a fraction and a percentage as they stand. Giving the discount instead of the price.
3 mistakes explainedMultiplying the powers instead of adding them. Reading a power as multiply by the index.
5 mistakes explainedOnly one favourable outcome counted. The boundary value counted in.
3 mistakes explainedOnly the count reduced. Only the total reduced.
3 mistakes explainedA counterexample offered without testing it. Examples offered as a proof.
5 mistakes explainedAdding the difference instead of scaling. Losing a factor of ten in the units.
3 mistakes explainedAdded when the hypotenuse was already known. The root taken before the squaring.
6 mistakes explainedAccepting a position that is not a whole number. Answering from a property of the number instead of solving.
6 mistakes explainedThe extremes added rather than subtracted. The largest value given as the range.
4 mistakes explainedA full turn given as the answer. A quarter turn given for a half turn.
3 mistakes explainedCutting the digits off instead of rounding. Rounding a 5 down.
5 mistakes explainedA ratio simplified with the wrong divisor. Dividing by one part instead of the total parts.
6 mistakes explainedCollecting the letters with the wrong sign. Repeating the operation instead of undoing it.
7 mistakes explainedMinus b used without dividing by 2a. Only the square root part divided by 2a.
5 mistakes explainedAdding the front numbers instead of multiplying. Counting the zeros instead of the places moved.
4 mistakes explainedA turning point given a nature it cannot have. The derivative set to zero and solved wrongly.
4 mistakes explainedLeaving the root on the bottom. Losing the sign when a root multiplies itself.
3 mistakes explainedThe choose number left out of the term. The minus dropped from a negative term.
3 mistakes explainedThe inside function never differentiated. The outer power dropped.
5 mistakes explainedA surd left unsimplified. The coefficient not halved when completing the square.
8 mistakes explainedA y-coordinate used as the intercept. Only part of the equation divided.
7 mistakes explainedA zero left out of the count. The group sizes attached to the wrong means.
3 mistakes explainedThe mean given where the median was asked for. The middle position counted wrongly.
6 mistakes explainedAny repeated value taken as the mode. How often it appeared given instead of the value.
6 mistakes explainedDivided by n rather than the root of n. The population standard deviation used unchanged.
4 mistakes explainedA count given where a probability was wanted. The complement given as the same number.
3 mistakes explainedOnly one term of the product rule written. The product rule terms subtracted.
3 mistakes explainedThe ratio written the wrong way up. The rearrangement done the wrong way.
4 mistakes explainedA negative root kept as a length. Only two sides counted.
5 mistakes explainedA multiplier applied to only one component. A scalar multiplier ignored.
3 mistakes explainedOne component added, the other subtracted. The components multiplied.
3 mistakes explainedA side of the shape given for a different vector. An arrow travelled the wrong way without a sign change.
3 mistakes explainedOnly two of the three dimensions used. Surface area given where volume was wanted.
A particle given a charge it does not carry. Electrons not matched to protons.
8 mistakes explainedA metal property given as an explanation. An element put on the wrong side of the table.
4 mistakes explainedA bacterium given a nucleus. Membrane-bound organelles given to a bacterium.
6 mistakes explainedA chemistry term swapped for a similar one. A common gas named at random.
3 mistakes explainedCurrent thought to be used up round the circuit. Parallel branches thought to change nothing.
6 mistakes explainedAdding mass thought to lower density. Density and mass treated as the same thing.
8 mistakes explainedA decomposer counted as a producer. A feeding group given the wrong definition.
8 mistakes explainedA physics term swapped for a similar one. Conservation of energy read as perfect efficiency.
7 mistakes explainedA famous scientist attached to the wrong idea. Animals thought to change themselves to suit the environment.
4 mistakes explainedAdding the quantities together. Balanced forces expected to produce acceleration.
8 mistakes explainedA genetics term swapped for a neighbour. Alleles thought to blend.
3 mistakes explainedA muscle given an action it cannot cause. Muscles thought to push as well as pull.
6 mistakes explainedA product of respiration misremembered. Breathing and respiration treated as one.
3 mistakes explainedA property offered as a rock type. A rock type matched to the wrong formation.
7 mistakes explainedA separating method matched to the wrong job. Dissolved solids thought to be filterable.
6 mistakes explainedA number from the question copied out. Multiplying where you should divide.
4 mistakes explainedA gas named that is barely in the air. A gas that is not a greenhouse gas chosen as one.
4 mistakes explainedEvery atom given a full outer shell. Period number used for outer electrons.
4 mistakes explainedA metal denied being a metal. All metals treated as equally reactive.
4 mistakes explainedA job given to the skeleton that is not its own. Another tissue named at the joint.
4 mistakes explainedA biology term swapped for a similar one. Environmental variation labelled genetic.
An apostrophe added after the s on an irregular plural. An apostrophe used to make a plural.
4 mistakes explainedA comma between the subject and its verb. A comma dropped inside a phrase that should stay whole.
4 mistakes explainedA general assertion with no method behind it. Context listed instead of used.
3 mistakes explainedA near twin that sounds or looks the same. Affect and effect swapped.
4 mistakes explainedA motive invented that the text does not support. The behaviour repeated instead of what it shows.
5 mistakes explainedA speech verb that fights the feeling. A technique that works against the wanted effect.
4 mistakes explainedNo comma before the closing speech mark. Speech not started with a capital letter.
3 mistakes explainedA complex sentence called compound. A participial opener mistaken for a clause.
5 mistakes explainedA letter doubled that should be single, or single that should be double. The i and e the wrong way round.
3 mistakes explainedA noun ending invented for the verb. The root spelled through unchanged when the ending changes it.
3 mistakes explainedThe continuous form chosen for the simple past. The future chosen for the past.
3 mistakes explainedA content word offered where a joining word was asked for. An adverb identified as an adjective.
4 mistakes explainedA meaning chosen because it sounds connected. A word from the same scene, not the same meaning.
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