Thursday, February 23, 2023

High School Writing Tip Sheets - Common Grammar and Punctuation Errors

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For the past few years I have been teaching high school writing in our homeschool tutorial co-op. Having seen several groups of students through the courses, I've noticed some issues and questions coming up regularly. I hope these Tip Sheets will be helpful to my students, their parents, and perhaps to other students and parent/teachers as well.

I had always intended to write an article highlighting some of the most common grammar and punctuation errors that writers make, and somehow never got to it. Hopefully this post will cover those and provide a quick reference point. The English language has so many rules, and the rules have so many exceptions, that it can be hard to keep everything straight! And everyone makes mistakes! So don't be too hard on yourself if you have trouble remembering some of the rules, or if errors slip past you when you proofread. Learn the rules as best you can, and take particular note of the things you struggle with. (Probably the ones your teacher most often marks in your papers!)

Spelling and Homophones

Almost every computer program you might use for writing an essay or story will flag your spelling mistakes, usually with a squiggly red line underneath. So I'm not about to give you a spelling lesson here! I'll just remind you to watch for those squiggles when you proofread. What your program is unlikely to catch for you is a word spelled correctly but used incorrectly. Homophones (words that sound the same but are spelled differently and have different meanings) are the most common culprits. Here are some examples:

rain - rein - reign
then - than
wear - where - ware
meet - mete - meat
affect - effect
to - too - two

There are dozens more! Unfortunately, there's no quick trick to catch them in your writing, other than doing a bit of checking in a dictionary if you're not sure. If you have a parent, sibling, or friend that can do a final proofread for you, ask them to watch for these. Sometimes often-used phrases and idioms can fall prey (not pray!) to the "sounds like" error too. For example, some people would write (not right or rite!) "for all intensive purposes" but the correct phrase is "for all intents and purposes". 

Another homophone type error that I've seen a lot is writing "would of" or "could of". It's wrong. Most of us pronounce it that way, but those are the contractions for "would have" and "could have" and should be spelled with an apostrophe, like this: "would've" or "could've".  That transitions nicely to the next common problem I want to address . . . apostrophes.

Using Apostrophes Correctly

Apostrophes are used to take the place of missing letters in contractions, and are used along with the letter S to show possession. There are a couple of exceptions, but let me say it in the strongest possible terms: DO NOT USE AN APOSTROPHE S TO MAKE A PLURAL. Do not sign your Christmas card: "Love from the Smith's". Feel free to politely tell your mom about this rule if she's the one that sends those cards. Politely! 

Add the apostrophe S to talk about the house or the dog that belongs to the Smith family: the Smith's house and the Smith's dog. If the dog has a toy, it is the dog's toy. More than one toy? The dog's toys. If the possessive noun is a plural that ends in s, it is not necessary to add another s after the apostrophe, If there are several dogs that own those toys, they are the dogs' toys. 

Apostrophes take the place of missing letters in contractions. Some examples are:

cannot = can't
I will = I'll
did not = didn't
they are = they're
she is = she's
it is = it's (take note of this one!)

And many more. So when you are trying to decide if an apostrophe belongs in a word, ask yourself if it is a possessive, or if the apostrophe take the place of missing letters.


A pronoun is a stand-in for a noun. This is pretty basic. However, mistakes occur most commonly with possessive pronouns and with noun/pronoun agreement. 

Possessive pronouns, unlike possessive nouns, do NOT use an apostrophe:


Notice the last one. The difference between "its" and "it's" trips up a lot of writers! In the contractions examples, I included "it's" which is a contraction of "it is". The apostrophe takes the place of the missing letters. If something belongs to it, there is no apostrophe, because "its" is a possessive pronoun. The same rule applies to the homophones "your" and "you're" The personal pronoun doesn't have an apostrophe, the contraction does. Finally, a simple rule to remember! 

Noun/pronoun agreement simply means that you use the correct pronoun to match its antecedent (the antecedent is the noun the pronoun refers to, and it should come before the pronoun). Plural nouns needs plural pronouns, singular nouns need single pronouns, male nouns need male pronouns, and female nouns need female pronouns. For objects and animals, use the pronoun "it" unless it's a pet that has a personal name.

people, girlfriends, insects, Max and Ruby (plural) = they/them/their/theirs
person, friend, puppy (singular) = he or she/him or her/his or hers/it/its
guy, boyfriend, George, Clifford the Big Red Dog (male) = he/him/his
woman, girlfriend, Maria, Princess the Cat (female) = she/her/hers

For informal writing, and in fiction, it's often okay to use plural pronouns like they/them/their for a single person, when the person's gender is unknown or irrelevant, or if it would be awkward to write neutrally. And after all, that's how we usually talk! So the following sentence would probably be fine in a story:

The detective had seen a shadowy figure step into the hallway, but now they were gone.

It's unknown whether the figure is a man or a woman and it might result in an awkward sentence to use a gender neutral singular pronoun. However, if the shadowy figure is clearly identified, then the matching pronoun should be used, like this:

The detective had seen Joe Boxer step into the hallway, but now he was gone.

And one more pronoun problem is using the personal pronouns "I" and "me" incorrectly. Most of the time, people get this wrong when there is another person involved. And most people can figure out the correct pronoun when they imagine the sentence without the added person. Here are a couple of examples:

Me and Bert went to Sesame Street.
Unless this is Cookie Monster speaking, this should be "Bert and I" because no one else would likely say "Me went to Sesame Street." 

Cookie Monster shared the cookies with Bert and I.
Surely "I" is more proper? Many people think so, but in this case "me" is correct because you wouldn't say the cookies were shared "with I". At least I hope you wouldn't, because it's incorrect.

It's less common, but sometimes writers misuse he/him and she/her the same way. It all comes down to whether the pronoun is the subject or the object, and that's an entire grammar lesson on its own!

Punctuation Problems! 

There are entire textbooks dedicated to correct punctuation and grammar and I can't summarize it all here, especially since this article is already quite long! Punctuation matters, just like spelling and correct capitalization matters. Sloppy, incorrect, or missing punctuation can change the meaning of your words and sentences, and make your essay or story very difficult to understand.

You're never "keeping it real" with your lack of punctuation and proofreading, you're keeping it unintelligible. ~Austin Kleon

Commas and quotation marks cause a lot of confusion for students! 

The correct use of quotation marks in dialogue is covered in my article: High School Writing Tip Sheets - Writing Dialogue. If you need to quote sources in non-fiction writing, you can find out how to do that in my article: High School Writing Tip Sheets - Citing Sources.

So let's briefly discuss commas. Many writers think the rule is that you put a comma wherever you would pause when speaking. This mistaken idea probably comes from the advice to pause briefly wherever there's a comma if you're reading aloud. In any case, it's much too simplistic a rule and just doesn't work. Where do you need a comma? Broadly speaking, use a comma to set apart an exclamation or term of address from the rest of sentence; to set apart words in a list; and to separate clauses in a complex sentence. That's a very simplistic list and there are rules (and exceptions, of course!) for each, but this is just a brief lesson, so here we go.

I was working on the proof of one of my poems all the morning, and took out a comma. In the afternoon I put it back again. ~Oscar Wilde

An exclamation like "okay" or "well" at the beginning of a sentence should have a comma. Or an exclamation point. If you've watched Interjections from Grammar Rock, you'll know this one. Here's a couple of incorrectly punctuated sentences, followed by the correct versions:

"Hey tell your friend to watch where he's going."
"Well no I didn't notice that."

"Hey, tell your friend to watch where he's going."
"Well, no, I didn't notice that."

If a character is speaking to someone and uses their name or some title that takes the place of a name, that is a term of address and should be set apart with a comma.

"Billy go get the car."
"You finished your homework right Billy?"

"Billy, go get the car."
"You finished your homework, right, Billy?"

Commas should separate the items in a list. This is what the Oxford comma debate is about. Personally, I'm Pro-Oxford comma, but many style guides do not require it any more. Find out what your teacher, professor, or governing style guide prefers. In any case, you're unlikely to ever be considered wrong to include the Oxford comma, but you could be considered wrong if you omit it. I'll let the memes make my point on this one!

To be clear, the original was photoshopped
to remove the commas that were there,
but it's an example of why the Oxford comma is important!

This one is just funny! Grammar nerd humor.

Hardest to explain is how to use commas to set apart clauses in a sentence. Again, very broadly, a dependent clause (one that is not a complete sentence on its own) is usually set apart from the rest of the sentence with a comma. You'll see lots of examples of that use in this article. The other side of this coin is writers using commas to join independent clauses together. We call it a comma splice, and it's just a run-on sentence, but with commas. It's not okay. 

And a final word about sentence fragments. In most non-fiction writing, you should always use complete sentences. In creative non-fiction (descriptive essays or memoir essays, for example) and fiction writing, sentence fragments can be just fine. 

Whew! That was long! I will refer you to one more previous article, and that is High School Writing Tip Sheets - Proofreading Properly. Your first drafts of writing can be very rough. It's as you refine your work and edit it for clarity that you can also watch for any errors like these and correct them. Check out the proofreading tips for ideas on how to maximize your chances of finding all the mistakes before submitting your paper for a grade!

Did that answer your grammar and punctuation questions? What other questions about high school writing do you have? Leave a comment and let me know! 

This post is part of the Write 28 Days Blogging Challenge hosted by Anita Ojeda. Find all my posts for the 2023 challenge here: Write Something Somewhere

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