A Grammar Rule I Didn’t Know

Over the years, I’ve tried to pick up most grammar rules (who vs. whom, further vs. farther), but the other day, I heard a basic grammar rule that was new to me…

What’s the difference between which and what?

For example, if you’re looking at a dessert menu, would you ask your friend:
a) “What dessert are you going to order?”
b) “Which dessert are you going to order?”

The correct answer is…


Here’s the rule:

* You use “which” when there are a limited number of things to choose from. (“Which of her brothers is the cutest?” “Which seat did you choose in the car?” “Which pizza toppings will you pick from this list?”)
* You use “what” when there are an unknown (or very large) number of things to choose from. (“What country is he from?” “What is your favorite book?” “What kind of cake would you like for your birthday?”)

I fully realize this is the nerdiest post on Cup of Jo to date, but you guys seem to love grammar, so I’m going for it!!!

So: Did you know it? Do you have any grammar pet peeves?

P.S. Good grammar is sexy.

  1. Bonnie says...

    I have lots of grammar pet peeves…
    1. Using “myself” incorrectly, as in “You can call Joe or myself.”
    2. The fairly new use of the word “ask” as a noun, as in “That’s a pretty big ask.”
    3. “I seen it.”
    4. This odd, recent trend of adding “ing” to verbs that were fine as-is. Why would you say “I’m loving that” or “I’m wanting to know” when you could say “I love that” or “I want to know.” This makes no sense!!
    5. Using the wrong pronoun form, as in “Him and I are going to the store.”
    Not grammatically incorrect, but why do so many people at work constantly talk about “reaching out?” Why so dramatic? Are we drowning? What happened to “contact me” or call or email?
    So many others…

  2. Kathleen Flynn says...

    Folks often use I, the nominative case pronoun, when they should use me, the objective case pronoun, for example, “Just between you and I.” As object of the preposition between, the pronoun should be the objective case me.

  3. Love this. Thank you for sharing this informative post.

  4. I actually did know this one! Two biggest pet peeves: affect vs effect, and this new one I’ve been seeing all over Instagram, realist vs realest. I actually saw a comment where the person tried to correct the other who ‘supposedly’ had it wrong, but the correction was not. the. right. correction.

  5. Love any excuse to put a new grammar rule to use!

  6. I love a good grammar lesson! My pet peeve is “fewer” vs. “less.” I see “less” used incorrectly in national, big-budget commercials everyday. It drives me bonkers.

  7. What about a post on lay vs lie. Oy!

  8. Not sure if anyone posted the rule of thumb for who/whom but there is a trick! If you’d use “he” or “she”, use “who” and if you’d use “her” or “him” use “whom”. Like if you’d say you’d “give it to him”, you could say “Whom will you give it to?” or “To whom will you give the gift?”

  9. I’m not sure if I’ve ever heard that one either! Maybe I have…in any case, thanks for posting!

  10. I never knew this! My biggest pet peeve for grammar is the incorrect use of “its” versus “it’s.”

  11. Love grammar rules! Do you know the rule for correct use of ‘which’ and ‘that’? It’s another one that appears to have been forgotten.

    My pet peeve is incorrect use of ‘than’ and ‘then’. I see it a *lot* in blog posts and comments.

    Grammar Rules!

  12. This is great! I did know this rule, but that’s because I have my Bachelors in journalism and I write for a living. Needless to say, I have many grammar pet peeves. One of the ones that’s been especially bothering me lately is the difference between over and more than. You only use over when you’re talking about spacial things. If you’re talking about numerical things, then you use more than.

  13. In our world of emojis and text speak a little dose of nerdy grammar is something we all could use! love these posts!

  14. The rules that blew my mind recently were the correct usage of an ampersand (should only be used to collect proper nouns, and sparingly); and that grey = English, while gray = American. So now when I see Americans write “grey,” it’s like they’re pulling a Madonna accent.

  15. I love the grammar posts. My pet peeve: “should have went”! I hear people saying this every day. I can’t stand it. Have even heard it several times on ESPN.

  16. I’m a foreigner (Greek and got to learn a few languages over the years) and I find posts like this really funny (sorry don’t mean to be offensive). It just that English is such a simple language and can’t understand how hard is it do tell the difference in things such as this you mention or your and you’re, really…

  17. I am such a grammar freak! I hate when people say “could of” instead of “could have”. I also strongly dislike when people on the phone say “this is her” instead of “this is she”. – Sarah

  18. I actually think I knew this, but instinctively not consciously – I love when people explain grammar though as I often can’t articulate why I follow certain grammar rules, I just know them in my gut. thanks for this!

  19. I am a grammar nerd too, Joanna! I find that the older I get and the less I truly learn each day, the more I struggle with proper grammar. I am contemplating enrolling in a college course (or 2!) just to keep my brain challenged. Perhaps an English class?

  20. As a professional translator whose mother tongue is not English, this was one of the first grammar rules I had to learn as a kid lol ;)
    (Can I also share some other pet peeves like adding an apostrophe “‘” after a noun to indicate the plural number and not possession or when people write “would of” when they mean “would have”) Sorry, nerdy lil me, I know i know… :P

  21. This is an easy one. I’m still confused with who and whom.

  22. I loved this! as a non native speaker, it’s fun not to be alone in our struggle with correct grammar. I’m an ESL teacher, and here’s a big grammar mistake (anyway, not used as taught in grammar books) I keep hearing on TV, in movies etc, so much so that I’m wondering if it is not an “Americanism”… so , I’ve learned and taught that you say: “I wish you would stop doing that” , and “I wish someone had told me that”, and not what is heard now: “I wish someone would have told me that. “Any thoughts? I’d appreciate it! Have a good day!

  23. Loved this post! Hadn’t consciously thought about it, and now I will!

  24. I can’t even begin to list my grammar pet peeves. For Christmas my work teammates got me a little poster that says “I’m silently correcting your grammar.”

    But if I had to choose, I’d say “number” vs “amount.” People NEVER get it right, and it drives me up the wall!

  25. I didn’t know this one!
    For me it bugs when people spell the word “lose” as “loose”. As in, “Did she loose her shoe?” instead of the correct spelling, “Did she lose her shoe?”

  26. I already knew that, but I teach grammar and writing for a living, so it’s not a shock to me that I did.

    I don’t think it’s nerdy at all to want to understand the languages you speak! After teaching international students, I find it fascinating that I spend more time in classes going over grammar concepts like who/whom with my American students, whereas my international students roll their eyes. :-)

  27. Haha- love it! I’m a grammar nerd too :) This one makes total sense!

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  29. grammarnerdy for the win! this post makes me so happy! :)

  30. huh. i did know this one from HS – we had a very good teacher, but I can never remember who vs. whom!

  31. Good to know! I’m going to look up the difference between “who” and “whom” now.

  32. A wonderful post, Jo! I’d love one concerning when to use that or which. Eg. Foods that contain sugar/foods which contain sugar. I’ve looked into this from time to time, but have failed to find a simple explanation that will stick in my head. x

  33. Another helpful trick with “which” and “that” is that “which” will almost always have a comma before it as it modifies the statement coming before it: “I’m going to post a comment on A Cup of Jo, which I’ve never done before.” ;)

    Thanks, Jo! Love your blog so very much.

  34. Haa!! Yes!! Free the inner geek! Xx

  35. thanks, sydney!! going to check out the site right now. xo

  36. @caroline, i never knew that about quote vs. quotation! i’ve been using that incorrectly, thanks for the tip xo

  37. There’s nothing wrong with nerdy! And good grammar is VERY sexy. :)

  38. LOVE this post!

  39. Seen/saw

    My whole family is constantly posting things like, “I seen that.” It’s plastered so frequently over the internet on their Facebook posts and I can’t handle it! Gives me hives, twitches, convulsions, and the like. How the hell might I tell them to just stop, already?!!!

  40. I’ve seen people write “for sell” instead of “for sale” and I want to gouge my eyes out.

  41. I am an English teacher and have many grammar pet peeves. My current annoyance is “could of” for “could have” which should be punishable by fifty lashes with a wet noodle.

  42. Love the grammar rules posts! Can you help with showed and shown. I always seem to screw this up! :(

  43. I love grammar, so I love this post. I will always think of this post when using what/which. It drives me nuts to hear or read the word anyways as well as are/ours.

  44. I love this post! I’m still learning English so You’re my teacher from now on! :) I love your blog Joanna! I’m addicted to it:))))

  45. Yes, I´m Spanish and I learnt it in my English classes long time ago.

    I think you don´t study English grammar at school, right? Here, in Spain, children have a subject called “Spanish language”, so we have to study all the gramma rules for Spanish. In my opinion it´s really important to know your language.

    Saludos desde Sevilla!!!

  46. I always get stuck writing text messages, wondering if I should write “neither” or “niether”, the more I think about it, are they two different words or am I just saying the same word in a differ accent? :/

  47. Now I’m doing a blog I have become more conscious of grammar – and was reading one of my kids books yesterday – did not know this rule but maybe it’s done unconsciously? Whichever!

  48. Yay ! Thanks a lot for this post . I read you from Spain and I’m about to take an english exam in three weeks (for a job ) and this is a lot of help ! Keep these posts comming pleeeeease :)

  49. being a foreigner, i did know that rule! :))) love your blog! cheers!

  50. This is why I love your blog! You post about this and that and even grammar rules. It’s so interesting and awesome!

  51. I’ve learned english for 9 years as foregin language, and we’ve learned thet rule. :-)

  52. This is awesome. I love grammar!

    My biggest pet peeve is quote vs. quotation. “Quote” is a verb, so you can quote an author, etc; “quotation” is the noun, so instead of “quote of the day,” it should be “quotation of the day!”

    I also get really bothered with use vs. utilize – “use” is for when something is used for its actual purpose, like “I use a knife to cut bread.” “Utilize” is when you use something in a way that was not initially intended, like “I utilized a knife to pick a lock.”

    • I love that explanation! I’m forever corrector our technical documentation (I’m a techwriter) because technical people LOVE to use “utilize” when “use” is a perfectly fine word.

  53. Mind blown! I love it!

  54. This makes the hair on the back on my neck stand on end: “He is the kind of person that likes….” He is the kind of person WHO likes…..

  55. I too love these grammar posts. I struggle with “who” vs. “whom”, so I tend to avoid using “whom”…I should read up on the usage rule! My pet peeve is seeing “it’s” when it should be “its” :)

  56. I am very serious about grammar! English is my second language and I’m always checking and re-checking my posts. I subscribe to a web-app called Grammarly and this has lowered my grammar stress level ;)

  57. Less v. Few is my pet peeve rule that I often hear broken. And it’s a similar rule- few when you can count the options and less when the thing you’re describing can’t be counted (less emotion, fewer jellybeans).

  58. Looks like you have a new recurring post topic! :) I think I knew this at one point but it is always good to refresh!

  59. I knew this, but only because I had to learn it in Spanish, and then teach it to my students.

  60. I had a college professor beat the difference into me, but I love a good grammar rule! A favorite site to always read fun grammar info is Grammar girl (…my mom and i are always emailing about things we learn from her!

  61. Love it! Thanks for the new grammar rule for me too!

  62. absolutely love the nerdy posts!!! keep it up :) xxx

  63. As a non-native speaker, I am pretty proud to say that I did know this one.

    Who vs. Whom still confuses me a bit.

    Anyway, I loved this post too!!!

  64. gc says...

    Love it! Keep bringin’ the nerdiness!

  65. I love this! Reminds me of my days in Spanish class learning the differences between “those” and “these”, which you really don’t think about being necessary until you realize how much you use those words!

  66. I love a good grammar rule! Keep ’em comin’!

  67. love this post. Own the nerdy. Own it, girl!

  68. Love this post! I think you should start doing weekly or even monthly posts on grammar rules.

  69. This is great! I’ve read about which vs. what several times but the lesson has never stuck. This one will, I’m sure!

  70. RB says...

    This is great — I love your grammar posts!
    I have a question for you and your lovely readers: do you “home” in on something or “hone” in? My boss and I have been debating!

  71. I’m a writer/editor and love stuff like this. Thanks for sharing! I’ll always think of the rule when “what/which” comes up.

  72. Love this post! I struggle with people who say “I could care less” when it should be “I could not care less”. Not a big deal.. I just notice it more often than not.

  73. Love this! One of my (many!)grammar peeves is using since in place of because. Since should only refer to time!

  74. How cute are the kitties! I love thiose pictures.

  75. It drives me crazy when people don’t know how when to use “I” vs “Me”- maybe you could do your next nerdy grammar post on that! You should be able to remove the other person from the sentence and it will still read correctly. For example, “Michael and I went to the store.” Not “Michael and me went to the store.” You would never say “me went to the store”. There are many more examples of the same rule… my mom drilled it into us!

  76. Grammar nerdiness is awesome, and I fully support, but can we talk about those kitties for a sec?!? So sweet!

  77. Thank you from nerdy grammatical UK. I think I use them correctly instinctively but do not remember being taught it.

  78. haha love it! my grammar pet peeve (or one of them) = “the reason is because …”

    it’s “the reason is that …”! or “[i was late] because …”!

  79. Hmmm I’ve never really thought of that one! I’m sure my sister-in-law(she’s always talking about grammar) probably knows this one. Thanks for sharing! :)

  80. I did not know this! I’m definitely going to remember this from now on :) also probably smugly point out someone else’s error!

  81. As someone who works in the advertising world, I really appreciate learning tricks like this. It will help with copy editing moving forward. Thank you for sharing!


  82. Love these posts. The nerdy content on Cup of Jo is some of my favorite, including the more personal posts – it seems true to who you are, and I love it!

  83. Ha! It’s funny how people who learned English as a second language are familiar with these grammar rules, whereas native speakers struggle with them. I cringe everytime I read ‘then’ instead of ‘than’or ‘would of’ instead of ‘would have’. But I know that the same happens in every language. I probably make a few grammar mistakes in Spanish myself, but when you’re used to them, you don’t notice. Besos!

  84. i have always been a grammar nerd (hello, degree in english) but i actually learned this rule in high school while studying spanish! we went over question words and learned the difference in spanish between que (what) and cual (which), and that translated (literally) to english.

  85. My grammar pet peeve is when people use the word “which” wrong, like, “I actually like vanilla ice cream which, it’s not my favorite but I don’t hate it.” Once I heard it the first time and it gave me that nails on a chalkboard feeling, I can’t help but notice it. Even when my husband does it I yell, “You used “which” wrong!”. Which is not the same as but! It only connects ideas that relate to each other! “I actually like vanilla ice cream which makes sense because all ice cream needs to get in my belly NOW!”

  86. Another grammar nerd…my pet peeve is the misuse of “I” and “me”. I hear it on TV, my boss uses it incorrectly…I could scream! People think “I” is always correct…when they don’t know the very simple rule. Arghhhh!

  87. No apologizing for ‘nerdy’ posts – if something is interesting, then it’s interesting, no need to qualify it.

    As an engineer this is a pet peeve of mine. Apologizing just makes it seem like there’s something bad about being curious about how the world works. The world is actually crazy cool though, and if you’re not interested in it, you’re nuts!

  88. “IRREGARDLESS”! Drives me crazy. Though it’s been accepted by some dictionaries as being correct now because so many people use it instead of “regardless.”

    Thanks for the post. Love all the comments.

  89. That made me think. I normally use them correctly, but hadn’t really thought about a rule – now I know!

  90. AG says...

    Composed of vs. comprise. URgh kills me!

  91. I love grammar! I *think* that I knew follow this rule fluently without having seen it actually explained… but now I’m going to pay attention to make sure!

    A couple others that I like:
    Less vs. fewer
    Which vs. that

  92. Love grammar posts! Keep them coming.

  93. I have a lot of pet peeves when it comes to grammar but the one that drives me crazy on a daily basis on Facebook is people saying “would of/should of/could of” instead of “would have/should have/could have” or “would’ve/should’ve/could’ve”.

    The other thing that drives me crazy about this, it that my computer thinks “should’ve” and “could’ve” are spelling mistakes! I’m Australian and my computer is American, so I just put it down to an incompatibility between us ;)

  94. Grammar is cool….after all, one of the taglines on my blog is “smart is the new sexy.” That, and I once devoted a whole post to the marvels of the exclamation point! :)

    I’d heard of this one before, but still get tripped up sometimes.

    Another one that drives me CRAZY is when people misuse the word “entitled” and use it when they’re saying “The book was entitled…”

    No, no, no… ok, will end my rant lol

  95. I’m proud to say that I did know this one. My biggest annoyance is when someone uses “I” when “me” is actually correct. I blame our second grade teachers for drilling “I” into us.

  96. LOVE grammar posts! Keep ’em coming!

  97. Reminds me of the much/many issue. It’s another one of those grammar rules that deals with things you can count. So like, “There are so many comments here!” vs “There is so much grammar nerd love happening right now.” One is a countable noun (number of comments), one isn’t (amount of grammar nerd love). As always with these things, now that you know about it, you’re going to hear everyone misuse it. EVERYONE.

  98. I absolutely love your blog AND this post! I am a total grammar nerd so I love this!

  99. ‘Suppose to’ and ‘use to’ as opposed to ‘Supposed to’ and ‘Used to’. So annoying!

  100. Pet peeve, ‘can we?’ when it should be ‘shall we?’ i.e. ‘Can we go to the zoo tomorrow?’ Er yes! It is physically possible, but you actually mean ‘shall we go to the zoo tomorrow?’ Also, ‘shall’ is such a lovely word!

  101. I did not know that. Bring on all the grammar posts, I love them!

  102. Good one!
    Pet peeves: ” a whole nother” vs. “a whole Other” and “anyways” vs. “anyway” eesh

  103. I just listened to the Reply All podcast episode about a man that is editing all of Wikipedia for use of the phrase “comprised of.” Apparently it’s wrong! “Comprises” means includes so you wouldn’t say “includes of.” I thought it was so interesting!

  104. You’re too good. I love it.

    I cringe at the use of the word “journal” as a verb.

  105. It is really not so different from “how many” vs. “how much,” right?

    Also, you comma commenters, if you bear with it, this recent New Yorker article will tell you more than you ever wanted to know about commas:

    Holy Writ by Mary Norris

  106. A who/whom trick I use is to rephrase the sentence using either he/she or him/her.

    For example, sentence in question:
    Whom do these books belong to? OR

    Who do these books belong to?

    Option A: They belong to him/her.
    Option B: They belong to he/she.

    Option A makes more sense.

    Now here’s the key – if it’s him/her, the word to use is WHOM. If it’s he/she, the word to use is WHO.

    Hope that helps!

  107. great tip!

    I LOATHE when people don’t use the correct version of they’re/their/ there. Or your/you’re. And when people say “seen”. For example, “I seen him last week”. Instead of “I saw him”. Drives me nuts!

  108. I am not the best with grammar, but incorrectly used “less” and “fewer” do drive me nuts—you can count fewer, and pour less.

  109. These posts are always so fun and fascinating! :)

  110. What about something that is a lot, but finite? Is it:

    “What state is he from?”


    “Which state is he from?”

  111. YAY! Keep these coming!

  112. This blog post solidifies you as the coolest blogger out there. Fashion sense + grammar intelligence + fun = your hubs hit the jackpot.

  113. I actually knew this! Another good one is further vs. farther (farther is distance, further is everything else) and I HATE when people misuse “utilize”. It’s not a fancy word for “use”!

    I also hate when people say the last word of an acronym again, like “ATM Machine”. It’s like saying “machine” twice -.-

  114. T says...

    The way I always remember this rule is by thinking of the phrase “Which of these” – so, for instance, you would say “Which of these shoes do you like?” Not, “What of these shoes do you like?” “Of these” reminds you that there is a set number of choices.

    Yay grammar nerdism! :)

  115. Loved this!!! Thank you!! I have to say, I would gravitate towards using which or what rather correctly as in the examples, BUT had no idea as to why!

  116. I was an English major, so this may be unfair. My pet peeve is the pluralization of family names, esp on holiday cards! I grew up as a Nelson, so the card to my parents should go to The Nelsons–not The Nelson’s. That possessive is only needed if you are referring to something that belongs to my family and then it would be s’. For example, The Nelsons’ Fat Cat. Now I am a Lewis, so our card could go to The Lewises. Simple plural. Simple plural, people! That’s it!

  117. Loved this!!!!! Thank you!!!! I would have to say I would gravitate towards saying which or what correctly as in the above examoles, BUT did not know why!

  118. Pinned :) I’m a sucker for grammar. Thanks!

  119. pet peeve: misusing “fewer” vs. “less”

  120. You are a nerd, but I dig it :). No shame in your grammar game.

  121. GRAMMAR!!!!!

    That’s how I feel about it :-)

  122. Love it! I always become annoyed when people say they are “good” when they are actually “well.” And when people say “these are them” or “those are them” when it should be “these are they” or “those are they.”

  123. Please don’t stop, because I love these grammar posts! I’m happy to be a nerd. :)

  124. Ha, I love the image you used for this post! I’m quite the grammar nerd, but I realize that colloquial English doesn’t follow grammatical rules in most instances. I do like to know the proper way to say/write things, though, especially for blog posts. I have a lot of pet peeves when it comes to this, but my biggest one is probably that people still don’t know the difference between when to use “your” or “you’re.” It only takes a second to really think about it!

  125. I love grammar (nerd!🙌) and had no idea! Now can you explain the oxford comma rule?

  126. LB says...

    Ooh! ooh! How about a grammar post about the use of is/are? I see more “Here is [or Here’s] my favorite photos…” and similar incorrect uses of the singular “is” with plural subjects all over the blog world. This grammar rule is my mom’s “thing” and clearly I have inherited it :)

  127. Lol I like nerdy posts! I don’t think I actually knew this was a rule, but I’m pretty sure I say it correctly anyway. I guess Grammar class in elementary school wasn’t completely wasted on me after all!

    Sweet Spontaneity

  128. I totally nerd out over this stuff, too, so thank you!! To this day, I still struggle with who vs. whom. Any good rules of thumb for that one?

  129. I think I’ve used this before, BUT I had no idea! Sometimes when I’m unsure, I just go with what “feels” right. It often works for me :)