The Wrath of Con-fusing Science Passages:
The biggest problem I see with students who struggle with Reading Comprehension science passages on the GMAT is that they focus on the wrong things. They focus on the scientific jargon they don’t know rather than the words they do know. They focus on dense descriptions of complex processes rather than simple analogies. And they focus on the ‘what’ rather than the ‘why.’
Here’s a short GMATPrep science passage. Take two minutes to read it and just try to get the main idea.
How’d it go?
When reading that passage, a lot of people start slowing down when they hit “gravity anomaly” in line 3 and then get stuck in line 8 on “negative gravity anomalies.” Some students will re-read it a bunch of times and try to power through, but they’re usually so mentally exhausted from slogging through the jargon that they ultimately miss the point of the passage. Other students, if they feel totally lost, might essentially give up, rush through the rest of the passage, and then go to the questions and start guessing. In either case, if I ask them to tell me what the passage is about, they’ll say, “It’s about gravity anomalies.” Which isn’t exactly wrong, but it’s missing the point.
So let’s switch gears for a moment and talk about another one of my favorite shows, Star Trek! Specifically, let’s talk about how the Star Trek writers use scientific jargon without losing the audience. Here’s a snippet from 1996’s Star Trek: First Contact.
The Borg (bad guys) are approaching Earth, with the Enterprise in hot pursuit:
Data taps a few buttons on his console: “Sensors show chronometric particles emanating from the Borg sphere.”
Picard: “They’re creating a temporal vortex!”
Riker: “Time travel!”
Now, what’s the point of that exchange? Is it about ‘chronometric particles’ and ‘temporal vortexes?’ Of course not! The point is that the Borg have a time machine!
But imagine if someone tried to watch Star Trek the way some students read GMAT science passages—by slowing down or stopping whenever they hit scientific jargon. That would be like hitting the pause button when Data said ‘chronometric particles’ and thinking, “What are those? I’d better rewind it and watch that part again.” That approach would never work—the viewer would be lost almost immediately, and they would miss the fact that two lines later, the point of the ‘chronometric particles’ line is revealed: that the Borg are traveling through time.
Okay, but why do we care that the Borg are traveling through time? Here’s what happens next:
As the Borg ship passes through the temporal vortex, Worf looks at Earth on the view-screen and realizes something suddenly looks different about it.
Worf: “Captain, Earth.”
Data (reading from his console): “The atmosphere contains high concentrations of methane, carbon monoxide and fluorine.”
Picard: “Life signs?”
Data: “Population, approximately nine billion—all Borg.”
Picard: “They must have done it in the past! They went back and assimilated Earth, changed history. We must follow them back, repair whatever damage they’ve done!”
So, why do we care? We don’t care about the technical information about methane, carbon monoxide, and fluorine levels. What we care about is that the Borg have gone back in time and taken over Earth, so the intrepid crew of the Enterprise has to go back in time to stop them. That’s what the whole movie is about.
(Also, I know that it’s kind of stupid to teach the GMAT using a movie that came out 22 years ago. But I wasn’t a GMAT instructor back then, so I have to do it now.)
So, back to our science passage. Let’s try it again, but try not to focus as much on the technical jargon of what they’re telling us, and instead zero in on why they’re telling us.
When a large body strikes a planet or moon, material is ejected, thereby creating a hole in the planet and a local deficit of mass. This deficit shows up as a gravity anomaly: the removal of the material that has been ejected to make the hole results in an area of slightly lower gravity than surrounding areas.
The first few lines describe a phenomenon: when something big hits a planet or moon, it smashes a bunch of stuff from the planet into space, leaving a big hole (crater) in the planet. The more mass something has, the more gravity it has (you learned that in high school, remember?). So where there is a crater, there’s less mass, so there should be less gravity in that spot.
Like the Star Trek writers, GMAT writers will often reveal a simple definition of tricky jargon right after the jargon, and that’s exactly what happens here. The writers define “gravity anomaly” right after introducing it: “an area of slightly lower gravity than surrounding areas.” So when you hit “gravity anomaly,” don’t freak out and don’t slow down—they’re going to tell you what it means in a moment.
The next question you should be asking yourself is: Why are they telling us this? Why do we care? Let’s find out.
One would therefore expect that all of the large multi-ring impact basins on the surface of Earth’s Moon would show such negative gravity anomalies, since they are, essentially, large holes in the lunar surface. Yet data collected in 1994 by the Clementine spacecraft show that many of these lunar basins have no anomalously low gravity and some even have anomalously high gravity.
Another classic GMAT move: They set up an expectation, and then subvert that expectation. We expect that the craters on the moon should have lower gravity (‘negative gravity anomalies’) than the surrounding areas, but the opposite appears to be true: some moon craters have normal gravity and some even have higher gravity! It’s not quite as exciting as a time travel sci-fi adventure, but it’s strange and interesting, and that’s really what this passage is about. That’s why we care.
And usually, when a GMAT passage describes an interesting conundrum or perplexing question in a Reading Comprehension passage, we should expect to then get one or more possible explanations. Here we go:
Scientists speculate that early in lunar history, when large impactors struck the Moon’s surface, causing millions of cubic kilometers of crustal debris to be ejected, denser material from the Moon’s mantle rose up beneath the impactors almost immediately, compensating for the ejected material and thus leaving no low gravity anomaly in the resulting basin. Later, however, as the Moon grew cooler and less elastic, rebound from large impactors would have been only partial and incomplete.
Aha. Long ago, when the moon was new and squishy, impact craters were immediately filled in with dense, heavy material from under the moon’s surface, so there was no missing mass and no lower gravity in those spots. But later, when the moon wasn’t as squishy, the opposite was true: the impact craters couldn’t rebound as much…
Thus today such gravitational compensation probably would not occur: the outer layer of the Moon is too cold and stiff.
Now, the moon is no longer squishy, so if it gets hit by something, the craters won’t be re-filled, and there should be lower gravity in those new craters.
So, again, in your own words, what was this passage about?
Now, take up to one minute and see if you can answer a question about it:
The passage is primarily concerned with:
a) Analyzing data from a 1994 exploration of the lunar surface
b) Reconciling two opposing theories about the origin of lunar impact basins
c) Presenting a possible explanation of a puzzling finding about lunar impact basins
d) Discussing how impact basins on the Moon’s surface are formed
e) Examining the claim that the Moon’s impact basins show negative gravity anomalies
Analyzing data? No. That’s the what, not the why.
Reconciling two theories? No, we only got one theory.
Presenting a possible explanation of a puzzling finding? Yeah, that sounds pretty good.
Discussing how impact basins are formed? Well, that was what they started with, but the real story didn’t get going until they got to the bit about the expectations being subverted. No.
Examining the claim that the Moon’s impact basins shown negative gravity anomalies? It’s not a claim—it’s simply a fact that some of the moon basins have the negative gravity anomalies, and others don’t. It’s a puzzling fact, but no one is disputing it. No.
The answer is C.
-On science passages, focus on the simple story and avoid getting bogged down with technical jargon.
-When you get to a really dense, technical part of the passage, don’t slow down—if anything, speed up.
-Always ask yourself, why do we care? Why are they telling us this? That will lead you to the main idea.