K. J. Bagnall

Writer. Editor. Illustrator. Mental Health Activist. Christian.

Three Common and Unexpected Grammar Mistakes To Look Out For


Anyone who’s seriously looked into English grammar, even just a little bit, knows it’s a bizarre creature. And the more you study it, the less confident you feel about using it correctly. Or maybe there’s a magical point where it all makes sense, which I just haven’t reached yet.

Today I’m going to share three grammar rules and scenarios that surprised me when I first learnt them, and always keep me on my toes. Well, there are certainly a lot more than three that do this, but we’ll keep it nice and simple for this post!


Photo by Elisa Xyz

Warning: grammar terms are used in this article. I explain some of the less-familiar ones, but be sure to follow links or do your own research for more definitions.

Lay, Laid, Lie and Lay

Okay, anyone know this one? Give yourself a pat on the back. This common grammar mistake is actually talked about quite a lot, but is tricky to remember.

Let’s start simple: Lay and Lie. Both are future-tense or present-tense (sometimes with an “s” added) verbs that pretty much describe the same action. So, what’s the difference? Well, “lay” refers to the object of a sentence and “lie” refers to a subject.

A note on subjects and objects

If you understand what I mean by object and subject, feel free to skip this section. Basically, a sentence subject is the noun or pronoun doing what the verb says, while the object is the noun or pronoun being acted upon by the subject. Don’t know what a noun or pronoun is?

Classic example: “The cat sat on the mat.” Who’s doing the sitting? The cat. So “(the) cat” is the subject. What’s being sat on? The mat. So ” (the) mat” is the object.


Original Image by Grant MacDonald, modified by Doug Belshaw

A more complicated example: “I rode my bike to school.” The subject is “I” as it’s “I” who does the riding. The object is “(my) bike”, as it’s being rode on. And what about “to school”? That’ll be explained later.

Back to Lay and Lie

Keeping with “the cat sat on the mat” classic, let’s see how Lay and Lie look in a sentence. “The cat lies on the mat.” So our subject — cat — is lying down on the mat. The cat is acting with its own body, and the mat happens to be there.

But how about this? “The cat lay the mat down.” Obviously cats can’t do this, but, more to the point, now something is actually happening to the rug. The mat is the one being laid down, but the cat is the one actually doing the laying.

But wait, there’s more…

Keeping up with me? Don’t worry, I had to read over the difference a few times myself to understand how it all worked. But this grammar rule has another trick to look out for.

After you lay a book on the table, you laid a book on the table. Laid is the past-tense form of the verb Lay. Pretty straight-forward, no problems so far. But after you lie down, you lay down. Lay is the past-tense form of the verb Lie.

Present-tense Lay becomes past-tense Laid, and present-tense Lie becomes past-tense Lay. So be careful, because the present-tense Lay and the past-tense Lay are two similar, but very different verbs. Confusing, right? Here’s a little chart that might help:

Lay and Lie Verb Tense Chart

That or Which

Both That and Which have two different meanings. That can be used to point something out (e.g. “That car over there”). Which can be used to offer a choice (e.g. “Which car is it?”). I’m not going to be talking about either of these meanings, but instead when they are used to add information.

Many use That and Which interchangeably, but they’re actually different! In Australian English grammar, at least. I’m not entirely sure about other countries, but this is definitely the Australian standard.

Technically speaking, That is used for defining clauses, and Which is used for non-defining clauses. Huh? Basically That is used to add clauses when the extra information is necessary to understand the point of the sentence, while Which is used when the extra clause isn’t vital to the meaning.

A note on clauses

Wait, you say, what’s a clause? A clause is a part or all of a sentence that contains a subject and a verb, plus sometimes other parts such as objects, adjectives, adverbs, etc.

They can be independent (i.e. could be a whole sentence by itself) or dependent (i.e. needs to be added to another clause to create a whole sentence). When using That and Which, you’ll be adding dependent clauses.

These dependent clauses can act as a noun (e.g. “What we ate for dinner last night” was delicious.), adjective (e.g. My friend, “who loves chocolate”, couldn’t finish the cake.) or adverb (e.g. We danced “until the clock struck twelve.”).

The difference between That and Which

Both That and Which add dependent clauses, but That adds a clause that directly affects the rest of the sentence, while Which adds a clause that is just extra detail. For example, “I like cars that are expensive.” means that I like (only) expensive cars. But “I like cars, which are expensive.” means I like cars, and (all) cars are expensive.

Image via pixabay (modified)

For those paying attention, I just used That and Which to add an a adjectival dependent clause. The difference is what the adjective refers to.

Makes sense? Oh, and when using That and Which in this scenario (i.e. to add a clause), never put a comma before That, but always put one before Which.

Past and Passed

This grammar situation is one I actively looked up myself. I stumbled across “Lay, Laid, Lie and Lay” while surfing the net, and “That or Which” was taught in one of my writing classes.

For years I’d always wondered when to use Past and when to use Passed, and finally got around to looking up the difference when someone asked me to look over their assignment.

Past is not a verb

A quick search was all I needed — Past is not a verb, it’s a noun (referring to the time period before the present). And Passed is a verb. Well, that clears things up!

Or is it?

Now Past and Passed were clearly distinguished in my mind, I continued on my merry way… and came across Past when I expected Passed. “We walked past the shops.” “The lake is past the trees.” Wait, isn’t Past a noun? How can it be used here? At first I considered it an error, but as I kept seeing it, surely that many people can’t be making the same mistake.


Image via pixabay

Everything but a verb

I did a little more research. And I was right, sort of. Past is a noun, and Passed is a verb. No change there. However, Past is also an adjective, an adverb and a preposition.


Okay, so adjective makes sense now I think about it. The “past student” referring to someone who was a student in the past, the “past winter” referring to a previous year’s winter — easy enough to understand.


Now onto adverb. I’m surprised how many people my generation don’t know what an adverb is (you do at least know what an adjective is, right?). An adverb describes how a verb is performed (think of it like “add verb”). For example, “he ran quickly”. “Quickly” is an adverb, as it tells you how he ran, or what sort of running he did.

But what is the meaning of Past as an adverb? Well, sort of what Passed means as a verb. Passed means to move from one side of something to another. As and adverb, Past means the same thing, but is paired with a verb.

Let’s take the example “We walked past the shops.” The verb is “walked”, and “past” describes how the walking happened. And how did it happen? The walking moved from one side of the shops to the other — the verb Passed the shops.

Whoa, wait, now you’re using Passed? Yes, because “the verb” is the noun and, as sentences must have verbs, “passed” is the verb. Of course if “the verb walked past the shops” then “walked” is the verb, and Past is the adverb.


Image via pexels


Still with me? Because this little “Past” word is very versatile, and has yet another use! Alright, so preposition. Ringing any bells? Don’t worry, I can never remember this one off the top of my head either. I blame not enough attention to grammar on the English syllabus.

A preposition links or orientates a noun (or concept) in regards to another part of the sentence. Let’s go back to “the cat sat on the mat.” We already know the noun is “(the) cat”, the verb is “sat” and the object is “(the) mat”. But what about “on”? Well, that’s a preposition! It lets you know where the cat is in relation to the mat — on top of it.

As a preposition, Past means “(to/on/at) the other side of”, “beyond” or “after”. For example, “The lake is past the trees.” To break this sentence down: “(the) lake” is the the subject, “is” the verb, “past” the preposition and “(the) trees” is the object. The preposition Past tells you where the lake is compared to the trees.

A note on time

In these past (note: adjective) examples, I’ve used Past and Passed in a physical, spatial sense. But they can also be used with time, in much the same way. Remember Passed is a verb, so “three weeks passed”, but Past is an adverb, so “three weeks went past”.

When specifying the time, you’re dealing with a preposition, so used Past. For example “half-past nine” or “past three o’clock”.

Surviving Grammar

Congratulations on reaching the end! Did you follow it all? If there are any grammar bits you’re still confused about, I suggest you research the rule on your own. Sometimes it takes one person to explain it in a particular way for it to click; apologies if my way of explaining doesn’t work well with you.


Image via pixabay

English grammar requires a lot of persistence to master. Fortunately may native speakers have instinctively picked up on quite a lot of the grammar, but there are always going to be those strange English rules to keep you on your toes.

So, good luck to all you English-nerds, writing-fanatics and anyone curious about this language we speak. English is a tricky, fluid language — I might share the story of why one day — but one rule at a time, we can grasp it’s swirling patterns.

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