- In this one, we're going to talk about sentence boundaries, specifically how punctuation marks the end of one idea and the beginning of another, or fully ends an idea. Now, if you watched the clauses lesson, you already know the most important rule, every complete sentence needs at least one independent clause.

If independent versus dependent still feels a little fuzzy, it's a good idea to maybe revisit the clauses lesson. For now, we'll assume you can recognize a complete sentence and understand the difference between a dependent and independent clause. So here's what the SAT actually tests.

Using periods, using semicolons, which we'll cover in a separate lesson, choosing the correct end of sentence punctuation, and avoiding fragments, run-ons, and comma-splices. So let's actually start with the bottom of our list here so that you know what I'm referring to when I mention them during this lesson, the things that indicate we've got a problem.

The first problem to be sure we can identify is a sentence fragment, which is just a term for an incomplete sentence. If you check out our example, "The cat in the tree," you'll notice that it's not a complete sentence since it's missing a main verb.

In this case, the verb that's missing is "is." The next sentence failure is a run-on, which is a result of joining two independent clauses without punctuation, like in, "I love to read I have so many books." That definitely needs a pause.

And the last sentence failure to be sure you can identify is a comma-splice, which is a type of run-on, but it uses a comma between independent clauses. SAT test writers love to sprinkle in comma-splices. Be particularly mindful of them. All right, now let's pivot from error types to acceptable constructions, starting with the acceptable usage of periods, the simplest punctuation mark in English.

A period ends a sentence with a complete full stop, the idea is over, finished, finito. If you have two complete sentences sitting next to each other, a perfectly valid way to separate them is to just end the first one with a period and start the next.

For example, "The experiment failed. The scientists were fired." Both of those ideas can stand alone, so a period works perfectly well to mark the boundary between them. But note, you cannot use a period unless you have two complete sentences.

A period might also pop up when the SAT is testing end of sentence punctuation. So let's check out what those question types look like. The end of a sentence is the end of an independent clause. Here are the three types of punctuation that are acceptable for that task.

A period, a question mark, and an exclamation point. Now let me clarify, we're not talking about linking two independent clauses together. We have a lot more options for that. We're talking about bringing one sentence to a full stop, which has a very serious sounding technical name, terminal punctuation.

You don't need to remember that, but it is kind of fun to say. Here are some examples. "I would like to win the lottery." A simple statement of fact. "Who won the lottery?" A simple question.

And "I won the lottery!" which has an OMG vibe to it that warrants the use of an exclamation point. Something to note, although we've seen exclamation points in the answer choices, we've yet to see one as the correct answer on the SAT.

That doesn't mean it will never happen, but SAT passages tend to be dry and academic in tone, and that's not the tone that exclamation conveys. So if you're feeling tempted by an exclamation point, be absolutely sure context clues support it. Furthermore, here's what seems to be trending in terms of how the SAT tests these, and that's making you decide between direct versus indirect questions.

Sometimes a sentence will ask a question directly. Other times, it simply reports a question someone studied or wondered about. Direct questions end with a question mark and actually ask a question, like, "Why did the experiment fail?" A clue you have a direct question is that it will typically have question word order, which is helping verb plus a subject plus the main verb, which you can see in our example with the helping verb, did, coming before the subject, experiment, and the main verb, fail.

Now, indirect questions, on the other hand, end with periods, not question marks, because they aren't really asking a question. And indirect question's function is to report a question someone else studied, or asked about, or even wondered about.

For example, researchers investigated why the experiment failed. Indirect question structure is also very basic. Statement word order is subject first, followed by a verb, which you can see reflected in our example. Experiment is our subject followed by failed, our verb.

There are also some words that signal you're dealing with an indirect question. So pay attention to when these words appear, especially in an end-of-sentence punctuation question. Here is the list. Investigated, studied, examined, wondered, asked, explored, considered.

If you see these verbs, the sentences are usually not asking direct questions, they are reporting a question that someone else or a group of people were working on. So the sentence likely needs a period. Let's see an example of how end-of-sentence punctuation can be tested.

This one falls into the easy category of questions. As per usual, if you want to try it out before seeing the explanation, pause now and resume when ready. All right, one clue you have an end-of-sentence punctuation question is that the answer choices all end in punctuation.

Now let's see what we have. We have some solid indirect question clues. The subject is archeologists. So a group that the writer is reporting on, and the signal word, wondered, tell us that the writer is reporting what this group of archeologists wondered about the topic in the blank, how early farmers moved water across dry land.

Well, given our clues, answers A and C with question marks can go because we know this does not match the structure or phrasing of a direct question. Now, if we compare B and D, we can see that D introduces direct question phrasing by putting the helping verb did into the answer option, which blends question word order with a period.

And that's a no-no. So our answer is B. Those archeologists wondered how early farmers moved water across dry land. And that's it for the two things we're gonna cover in this lesson.

Let's wrap up with the key ideas. First, be able to recognize problems, fragments, run-ons, and comma-splices. Second, a period ends or comes between complete sentences, and that's it. And finally, question marks are only used for direct questions.

If the sentence is simply reporting a question, it should end with a period. Once you start thinking about punctuation in terms of sentence boundaries, these questions become much easier to solve.