Young Geniuses · Ages 13 to 14
Error Analysis Spot the Wrong Step
Decide whether each worked calculation is correct. Five levels of printable error-analysis practice with answer keys.
The learning journey
Every activity is one step. Here is where this one fits.
- PlayLearn the idea in a game
- Practise(you are here)Lock it in on paper
- ReviewCome back and keep it sharp
- MasterTake on a harder challenge
- AchieveEarn a certificate
About Error Analysis Spot the Wrong Step
Marking someone else's work is a harder skill than doing your own, and a more useful one — a pupil who can find the wrong step in a worked calculation has learned to check, which is the habit that catches their own errors under exam pressure. Every statement on this page is a complete calculation with a stated answer, and roughly half of them are wrong. The wrong ones are not random numbers. Each is a genuine misconception: a dropped carry in an addition, a failed exchange in a subtraction, an extra row in a multiplication, an off-by-one table slip in a division, and at the higher levels the big one — evaluating left to right and ignoring that multiplication comes before addition. That last error produces a number that looks entirely reasonable, which is exactly why it survives unnoticed in real work. Because the wrong answers are plausible, a pupil cannot pass by spotting implausibility; they have to redo the calculation. True and False are balanced by construction, half of each on every page, shuffled with no run longer than three. All four operations appear across the worksheet. Eight statements per page with tick boxes, and each level downloads with its own separate answer key.
Common questions
- Are the wrong answers obviously wrong?
- No. Each one is a genuine misconception, so a pupil has to redo the calculation rather than spot an implausible number.
- What errors are covered?
- Dropped carries, failed exchanges, an extra row in multiplication, off-by-one table slips, and ignoring order of operations.
- Is the True/False split balanced?
- Yes, by construction — half of each on every page, with no run longer than three.
- Why teach checking as a separate skill?
- A pupil who can find someone else's wrong step has learned the habit that catches their own errors under pressure.
A hand for grown-ups
- Before you start
- These need thinking time, not speed. Set the expectation that a good puzzle is meant to take a while.
- While they work
- Resist jumping in. A long pause is a child thinking, not a child stuck — give it room before offering a nudge.
- Afterwards
- Ask "how did you work that out?" more than "is it right?". The reasoning is the skill; the answer is just the evidence.
- Watch out for
- Guessing to escape the discomfort of not knowing. Reassure them that being stuck for a bit is normal and fine.
- Away from the screen
- Play strategy games, do puzzles, ask "what comes next?" with patterns of objects. Reasoning is a muscle.
Where to go next
Chosen by the skills this activity practises.