What is an em dash, and how do you use it for ACT English?

An em dash is a piece of punctuation that high school students probably use extremely rarely (or never!). It's what you get when you type in two dashes and it autocorrects to one longer dash, you know, like this: - + - = —

This is, for certain, a piece of punctuation that will appear likely multiple times on most ACT English tests, and for sure, the absolute vast majority of high school students will have no clue how it is used or what to do with it.

Recently, I broke this down in a YouTube video, but we will simplify that here today as well.

First, use one of them to combine independent clauses (phrases that can stand alone as sentences) into a more complex sentence. There are multiple ways to do this in English (such as with a semicolon, a colon, or a comma with a FANBOYS conjunction), but an em dash is one of them. For students who never use this puncutation (which, again, is almost all of them), this is going to look strange, but that is no matter.

The 2 uses of the em dash

Here's an independent clause: I went to the grocery store.

Here is another independent clause: I forgot to buy milk.

To combine these together: I went to the grocery store—I forgot to buy milk.

Secondly, use two em dashes in the same sentence to set off nonessential information (in other words, use them like you would use parentheses). The trick here is very simple: if a sentence makes sense with parentheses, it will also make sense with em dashes.

Here is an example (with parentheses): The note left in Roger's locker (both encouraging and inspirational) was written on paper ripped from a spiral notebook.

The phrase "both encouraging and inspirational" is what is called nonessential. It simply means that if you took it out of the sentence, the sentence would flow and work perfectly well.

Nevertheless, you can see that the sentence would also function well with two em dashes, like this:

The note left in Roger's locker—both encouraging and inspirational—was written on paper ripped from a spiral notebook.

There you have it! Don't let little bits of punctuation remain a mystery when their mastery is rather simple.

If you want some free ACT prep cheat sheets that lay it all out in a few pages, then click here!