Main Idea

In this video, we're gonna talk about the main idea, one of the most common questions, especially on longer passages. So, almost always accompanies a big passage. Now, what is a main idea question? It's, it's the big picture, but that's a little bit vague. More specifically, it means why did the author write the passage?

What point is he or she trying to convey? Oftentimes, you will also see primary purpose of the passage instead of just saying what is the main idea. So, the question stem can differ a little, but both primary purpose and main idea essentially ask the question, why was this passage written. Now, to look for the main idea, it's not too difficult, because it usually comes at the beginning or at the end.

So, keep that in mind when we go through the main idea question here at the end. Look for words such as therefore, consequently, and as a result. I'm putting that there, because it sometimes happens, but it seems like the GMAT's becoming a little more savvy about this. So, over the years this isn't usually the case, especially on the harder passages, you won't have such a obvious flashing sign that the main idea is close.

Now, some basic strategies here, first one is, look for the main idea when you're reading the passage, and it goes back to actively reading. If you made the mental snapshots of the paragraphs and you have a sense of how everything ties together, it's very easy to answer or to put the main idea in your own words without necessarily having to go back and find that specific part of the passage.

But you should have a pretty general, good idea of what the main idea is after you read the passage for the first time. You should also know your wrong answer types in terms of main ideas because they have to make this a difficult question. They can't just make it really obvious, though, of course you wrote it for this reason.

So, they have to try to trick you, and how do they trick you? Well, they make the answer choice too specific. Maybe the answer's the perfect answer for, the second paragraph focuses on which idea. However, main idea's about the entire passage, so watch out for the too specific.

Sometimes, too general or just too vague, not specific enough, but this one is not nearly as common a wrong answer as the too specific. A common one is the perfect answer choice, but then something erroneous, something wrong is added that throws off the whole answer choice, and that something erroneous is usually at the end of the answer choice. It's important to read the whole answer choice instead of just reading a few words and thinking, oh yeah, totally talked about that.

Make sure you read the entire answer choice, because the error could be lurking at the end. Now, in terms of another good strategy, now that we've gone over wrong answer types, is how to find the main idea. Sure, you've, have a general idea once you've read the passage, but after you've done a few questions, you may have forgotten it.

You really wanna go back, you always want to go back to support your answers. So, where do you read? Well, reread the first paragraph and the last sentence of the passage, and almost always that's gonna give you what you need to answer the main idea question. Now, we're going to do just that here right now. Of course, here's our main idea question, which we'll come back to in a moment.

And what I've done here is reproduced the first paragraph, topic sentence of the middle paragraph, just to give you an idea of how that's probably not usually important, and of course the last sentence of the passage. If we read the very first paragraph up here, we'll see that there is not much of a main idea. They are just introducing the topic of, how dinosaurs have been thought of, in terms of their body temperature.

The second just talks about the findings itself. It's not until you get to the very end, while the link between metabolism and the growth rate is promising, paleontologists will need to collect more data across different dinosaur clades in order to have a better sense of the, the role mesothermy played. So, the passage is not, oh, mesothermy is definitely, for the study shows us that that's what dinosaurs were in terms of body temperature.

No, main idea of the passage is that, wow, this, this study touched on this interesting relationship, but we can't say for sure just how prevalent mesothermy was across different dinosaur groups, and that's the gist of the main idea. So, let's go back and now answer the questions, and notice that I paraphrase the answer before I went back to the answer choices. A, the connection between metabolism and growth rate is unclear.

According to the passage, it seems that the connection between metabolism and growth rate is relatively clear, but again this tends to be somewhat vague. We're just talking about growth rate in general, and so we can get rid of this for a couple of reasons. B, Dinosaurs were neither cold-blooded nor warm-blooded. They were mesothermic.

That is what the study suggested. Is that the same as the main idea of the passage? Again, the main idea is that they were probably, but more studies will have to done, be done to, to determine the extent of mesothermy. So, B is not representative of what the passage is actually saying. C, animals that have a slow growth rate tend to be cold-blooded.

Wow, ding, ding, ding. That, that's mentioned in the passage, but wait a second, that's not a main idea. That's just a specific detail in one of the paragraphs. D, Mesothermy would have allowed dinosaurs to catch smaller prey. Again, a detail in a paragraph, but not the main idea, which is E, Mesothermy may have been present in some dinosaurs.

Chris Lele
Lesson by Chris Lele
Magoosh Expert
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