--- title: "Spot the Error" url: https://erroneo.us/spot-the-error/ description: "A free, timed proofreading game: find the one wrong word in each sentence. Confused words, grammar, idioms and spelling, each round linked to the rule." type: interactive-tool section: "Play" date_modified: 2026-10-20 publisher: erroneo.us license: All rights reserved. Quote with attribution and a link. --- # Spot the Error > Every sentence below has exactly one mistake: a confused word, a grammar slip, a mangled idiom or a misspelling. Find it before the timer runs out, keep your streak alive, and learn the rule behind each one. ## How to play - **One mistake per sentence.** Everything else in the sentence is correct, so trust your first instinct. - **Ten seconds each.** The bar drains from green to red. Faster correct answers score more. - **Streaks multiply.** Every correct answer in a row adds to your streak bonus. A miss or a timeout resets it. - **Keyboard friendly.** Press Tab to move between words and Enter to choose. Press Enter again for the next sentence. - **Share your card.** At the end you get a spoiler-free grid of hits and misses to paste anywhere. ## What the rounds test The sentences are drawn from four of our language guides, so every answer links back to a sourced explanation: - [Commonly confused words](https://erroneo.us/language/commonly-confused-words/): *then/than*, *its/it’s*, *affect/effect*, *lose/loose* and dozens more. These are real words in the wrong place, which is why a spell-checker waves them through. - [Common grammar mistakes](https://erroneo.us/language/common-grammar-mistakes/): *should of*, subject–verb agreement across a long subject, and apostrophes in plurals. - [Misused idioms](https://erroneo.us/language/misused-idioms-and-phrases/): *tow the line*, *free reign*, *sneak peak*. Many are eggcorns, mishearings that make a kind of sense. - [Commonly misspelled words](https://erroneo.us/language/commonly-misspelled-words/): *definately*, *seperate*, *recieve*. > **Errors from your fingers, not your head?** If you know the right word but keep typing the wrong letters, that’s a motor skill. The free [typing trainer from allthingsN](https://allthingsn.com/typing/) drills accuracy before speed. ## All 36 sentences, with answers Every round is drawn from this list. Each answer links to the guide that explains the rule. 1. My sister is a much better swimmer then anyone else on her team. **Show the error** ~~then~~ → than. Comparing? Use than. Then is about time or sequence (first this, then that). [Confused words guide](https://erroneo.us/language/commonly-confused-words/#then-vs-than) 2. The new parking rules will effect everyone who works the night shift. **Show the error** ~~effect~~ → affect. Affect is the everyday verb meaning 'to influence'; effect is usually the noun for the result. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#affect-vs-effect) 3. The neighbors said their going to repaint the fence this weekend. **Show the error** ~~their~~ → they're. If 'they are' fits, write they're; their shows possession. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#their-vs-there-vs-theyre) 4. Every morning the cat waits patiently by it's bowl and meows loudly. **Show the error** ~~it's~~ → its. It's always means 'it is' or 'it has'; the possessive its takes no apostrophe, like his and hers. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#its-vs-its) 5. Hold the railing tightly so you don't loose your balance on the stairs. **Show the error** ~~loose~~ → lose. Lose (one o) means to misplace or fail to win; loose (two o's) means not tight. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#lose-vs-loose) 6. Fresh mint is a lovely compliment to a bowl of summer berries. **Show the error** ~~compliment~~ → complement. A complement completes or perfects something; a compliment is praise. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#compliment-vs-complement) 7. The principle reason for the delay was a shortage of spare parts. **Show the error** ~~principle~~ → principal. Principal is the adjective meaning 'chief'; principle is only ever a noun for a rule or belief. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#principal-vs-principle) 8. There were less people at the beach than we expected today. **Show the error** ~~less~~ → fewer. Fewer is for things you can count, like people; less is for amounts you measure. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#fewer-vs-less) 9. Let me know if your coming to the picnic on Saturday. **Show the error** ~~your~~ → you're. Expand it to 'you are': if that fits, write you're; your means belonging to you. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 10. Nobody could figure out who's umbrella was left in the meeting room. **Show the error** ~~who's~~ → whose. Who's means 'who is' or 'who has'; whose means belonging to whom. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 11. Our puppy gets far to excited whenever the doorbell rings. **Show the error** ~~to~~ → too. Too means 'also' or 'excessively'; 'too' has too many o's. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 12. Everyone was invited to the party accept my cousin, who was traveling. **Show the error** ~~accept~~ → except. Except means excluding (except excludes); accept means to receive or agree to. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 13. My grandmother gave me some great advise about planting tomatoes. **Show the error** ~~advise~~ → advice. Advice is the noun, a recommendation (it rhymes with ice, a thing); advise is the verb. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 14. We could not decide weather to hike the ridge or stay by the lake. **Show the error** ~~weather~~ → whether. Whether means 'if' and introduces alternatives; weather is atmospheric conditions. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 15. The trains sat stationery for an hour because of snow on the tracks. **Show the error** ~~stationery~~ → stationary. Stationary means not moving; stationery is writing paper (e for envelope). [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 16. The chef spent all afternoon baking a chocolate desert for the party. **Show the error** ~~desert~~ → dessert. Dessert is the sweet course (you want seconds, ss); a desert is arid land. [Confused words guide](https://erroneo.us/language/commonly-confused-words/#the-full-table-45-commonly-confused-words) 17. You should of seen the fireworks over the harbor last night. **Show the error** ~~of~~ → have. Should have shrinks to should've in speech and sounds like 'of', but 'should of' in writing is always an error. [Grammar guide](https://erroneo.us/language/common-grammar-mistakes/#9-could-of-for-could-have) 18. I would of called you back, but my phone battery died. **Show the error** ~~of~~ → have. Would of, could of and should of are always errors; write would have or would've. [Grammar guide](https://erroneo.us/language/common-grammar-mistakes/#9-could-of-for-could-have) 19. The box of old holiday ornaments are sitting in the garage. **Show the error** ~~are~~ → is. The verb must agree with its real subject, box, not the nearest noun, ornaments. [Grammar guide](https://erroneo.us/language/common-grammar-mistakes/#2-subject-verb-agreement-across-a-long-gap) 20. The corner bakery sells fresh muffin's every morning before seven. **Show the error** ~~muffin's~~ → muffins. Don't use an apostrophe to make a noun plural. [Grammar guide](https://erroneo.us/language/common-grammar-mistakes/#3-apostrophes-in-plurals) 21. The coach handed out new jerseys to Maya and I after practice. **Show the error** ~~I~~ → me. After a preposition like to, use the object form me. Drop the other person: you would never say 'to I'. [Grammar guide](https://erroneo.us/language/common-grammar-mistakes/#5-between-you-and-i) 22. The doctor whom we believe is the best in town is retiring. **Show the error** ~~whom~~ → who. Strip out 'we believe': the pronoun is the subject of 'is', so it stays who. [Grammar guide](https://erroneo.us/language/common-grammar-mistakes/#6-who-vs-whom) 23. After the long hike, all I want is to lay on the couch. **Show the error** ~~lay~~ → lie. Lay takes an object (you lay something down); lie does not (you lie down). [Grammar guide](https://erroneo.us/language/common-grammar-mistakes/#7-lay-vs-lie) 24. New employees are expected to tow the line during their first month. **Show the error** ~~tow~~ → toe. To toe the line is to conform, as runners put their toes against a starting mark. [Idioms guide](https://erroneo.us/language/misused-idioms-and-phrases/#toe-the-line) 25. The manager wanted to nip the office gossip in the butt quickly. **Show the error** ~~butt~~ → bud. To nip it in the bud is to stop something early, the way a gardener pinches off a bud before it flowers. [Idioms guide](https://erroneo.us/language/misused-idioms-and-phrases/#nip-it-in-the-bud) 26. The director gave the actors free reign to improvise the final scene. **Show the error** ~~reign~~ → rein. It's free rein: loose reins let a horse move freely. [Idioms guide](https://erroneo.us/language/misused-idioms-and-phrases/#quick-reference) 27. The whole crowd waited with baited breath for the final penalty kick. **Show the error** ~~baited~~ → bated. It's bated breath: bate means to lessen or hold back. [Idioms guide](https://erroneo.us/language/misused-idioms-and-phrases/#quick-reference) 28. The studio released a sneak peak of its new animated film today. **Show the error** ~~peak~~ → peek. It's a sneak peek, because a peek is a look; a peak is a summit. [Idioms guide](https://erroneo.us/language/misused-idioms-and-phrases/#quick-reference) 29. Irregardless of the forecast, we are still going camping this weekend. **Show the error** ~~Irregardless~~ → Regardless. Irregardless is a nonstandard blend that has never been accepted in Standard English; write regardless. [Idioms guide](https://erroneo.us/language/misused-idioms-and-phrases/#irregardless) 30. After years of cheating at board games, he finally got his just desserts. **Show the error** ~~desserts~~ → deserts. It's just deserts: what you deserve, not a sweet course. [Idioms guide](https://erroneo.us/language/misused-idioms-and-phrases/#quick-reference) 31. I will definately bring snacks for the road trip on Friday. **Show the error** ~~definately~~ → definitely. Definitely contains 'finite'. [Spelling guide](https://erroneo.us/language/commonly-misspelled-words/#the-table-50-commonly-misspelled-words) 32. Please keep the raw chicken on a seperate cutting board. **Show the error** ~~seperate~~ → separate. There's 'a rat' in separate. [Spelling guide](https://erroneo.us/language/commonly-misspelled-words/#the-table-50-commonly-misspelled-words) 33. You should recieve a confirmation email within the next few minutes. **Show the error** ~~recieve~~ → receive. Receive is one case where 'e before i after c' holds. [Spelling guide](https://erroneo.us/language/commonly-misspelled-words/#the-table-50-commonly-misspelled-words) 34. The lakeside cabin is big enough to accomodate our whole family. **Show the error** ~~accomodate~~ → accommodate. Accommodate is big enough to accommodate two c's and two m's. [Spelling guide](https://erroneo.us/language/commonly-misspelled-words/#the-table-50-commonly-misspelled-words) 35. It felt a little wierd to see snow falling in late April. **Show the error** ~~wierd~~ → weird. Weird is weird: it breaks the i-before-e rule. [Spelling guide](https://erroneo.us/language/commonly-misspelled-words/#the-table-50-commonly-misspelled-words) 36. Short power outages are a common occurence during summer thunderstorms. **Show the error** ~~occurence~~ → occurrence. Occurrence has a double c, a double r, and ends in -ence. [Spelling guide](https://erroneo.us/language/commonly-misspelled-words/#the-table-50-commonly-misspelled-words) ## Frequently asked questions **How does Spot the Error work?** Each round shows ten sentences, one at a time. Every sentence contains exactly one wrong word. Tap or click it (or move with Tab and press Enter) within ten seconds. A correct tap earns points plus a bonus for speed and streak; the red pen then shows the correction and links to the guide that explains it. **Is it 'affect' or 'effect'?** Usually, affect is the verb meaning to influence and effect is the noun meaning a result. If you can put "the" in front of it, you want effect . The commonly confused words guide covers the exceptions. **Is 'should of' ever correct?** No. It comes from how should've sounds in speech. Write should have or should've . The same goes for could of and would of ; see common grammar mistakes . **Why can't a spell-checker catch these?** Many of these mistakes are correctly spelled words in the wrong place, like then for than or reign for rein , so a spell-checker sees nothing wrong. Outright misspellings are usually caught, but spell-checkers aren't everywhere: not on handwritten forms, whiteboards or every text box. **Does the game save my score?** Only your best score, in your own browser's local storage. Nothing is sent to a server, and there is no sign-up. ## Sources 1. [Cambridge Dictionary, English Grammar Today: Affect or effect?](https://dictionary.cambridge.org/grammar/british-grammar/affect-or-effect) 2. [Cambridge Dictionary: There, their or they're?](https://dictionary.cambridge.org/grammar/british-grammar/there-their-or-they-re) 3. [Cambridge Dictionary: It's or its?](https://dictionary.cambridge.org/grammar/british-grammar/it-s-or-its) 4. [Harvard Law School Writing Center: Common language errors](https://hls.harvard.edu/academics/hls-writes/writing-center/common-language-errors/) 5. [Purdue OWL: Apostrophe introduction](https://owl.purdue.edu/owl/general_writing/punctuation/apostrophe_introduction.html) 6. [The Phrase Finder: For all intents and purposes](https://www.phrases.org.uk/meanings/all-intents-and-purposes.html) 7. [Wikipedia: Eggcorn](https://en.wikipedia.org/wiki/Eggcorn) 8. [Wikipedia: Commonly misspelled English words](https://en.wikipedia.org/wiki/Commonly_misspelled_English_words) --- Source page: https://erroneo.us/spot-the-error/ · More: https://erroneo.us/llms.txt