The little words it and this don’t carry a lot of meaning, but they are used in different grammatical contexts, and using the wrong word can be confusing.
It has three main functions:
- As a pronoun, it refers to a singular, non-human noun:
I saw a movie yesterday. It was awful!
When you turn on your computer, it tries to connect to the Internet.
- It sometimes appears at the start of a construction where it comes before the verb be or such “linking” verbs as appear or It is in the position of a subject, but it is not really a subject. It just fills that slot in the sentence. In terms of meaning, the main idea of the sentence comes in a that clause or to infinitive. These can occur after certain adjectives (it is clear that / probable that / important to / necessary to / difficult to…), and the choice of that clause or a to infinitive depends on which adjective you use. A similar itconstruction involves passive reporting verbs (it is thought/said/believed that…). The word it has no real meaning in these sentences, but it is necessary because the sentence needs something to fill the subject position. Notice that it refers forward to a new idea in these sentences.
It is important to wear sunscreen.
It is believed that tea may protect against some diseases.
- It also fills the subject position in many sentences about the weather, but it doesn’t have any real meaning.
It is hot today.
It is going to snow.
This also has two main functions, but it always refers back to a thing or idea that has already been introduced:
- As a determiner, this means this one (that the reader/listener can see or already knows about).
In this class, you will learn about the history of musical theater.
Look at this mess on the floor!
- As a pronoun, this can refer back to an entire idea, not just a single noun:
It is going to rain today. This means we can’t have a picnic.
The price of gas has fallen. This is one reason why people are driving more.
Writers should be careful with the second use of this to make sure that the meaning is clear. Sometimes it is preferable to include a noun that clarifies what this means, especially in complex academic writing:
The research was conducted in an urban high school in January during students’ regular science classes. Thiswas chosen because…
In the example above, it is not clear what was chosen: the high school, the month, or science classes. A better sentence would begin: “This subject/month/site was chosen because…”
The exercises on the downloadable handout will help your students practice these uses of it and this. In next month’s newsletter, I’ll look at this, that, these, and those.