Lesson 5: Choosing Punctuation for Effect
The writing "errors" considered the most serious have to do with marking (or not) clause boundaries, leading to run-on sentences, also known as comma splices. (I scare-quote 'error' since I think it's important to remember that any variation is usually based no some kind of linguistic knowledge. It may not follow the tradition expected for a particular genre of writing, but it's not just random and wrong.)
So once students can identify clauses, they can easily avoid these issues. The lessons in the Grammar section (Lessons 3.2, 3.3, and 3.4) are all good ways to identify subjects in order to identify clauses, and therefore avoid writing in run-ons/comma splices or fragments, if that’s your goal.
It’s important to keep in mind that there is not always a single correct way to punctuate a sentence. There are, for example, a great many ways to combine two independent clauses to make a coordinated complex clause.
You know that any clause must have a subject, and you can use the Tag Question test and the Subject-Auxiliary Inversion test to find the subject of the independent clause.
Now, let’s take two independent clauses:
I went to the store. I forgot to buy bread.
And combine them into a single sentence.
There are many correct ways to do it. Here are just a few.
I went to the store, but I forgot to buy bread.
I went to the store; however, I forgot to buy bread.
I went to the store; I forgot to buy bread.
Discuss how the various ways of punctuating convey different meaning and focus.