While researching a topic, a student has taken the following notes:Scientists have long sought to determine the origin of glass...
GMAT Expression of Ideas : (Expression) Questions
While researching a topic, a student has taken the following notes:
- Scientists have long sought to determine the origin of glass in Chile's Atacama Desert.
- A 2017 study concluded that ancient grass fires had melted the area's sandy soil into glass.
- In 2021, a different study revealed that the mineral signatures of glass samples were consistent with the mineral signatures of comet samples collected by NASA.
- That study concluded that the glass had formed as a result of a cometary explosion close to the desert's surface.
The student wants to describe how scientific understanding about the glass's origin has evolved. Which choice most effectively uses relevant information from the notes to accomplish this goal?
Scientists have long sought to determine the origin of the glass, with one study concluding that it formed when ancient grass fires melted the area's sandy soil.
Studies in 2017 and 2021 offered different explanations for the origin of the glass.
Mineral signatures of glass samples are consistent with those of comet samples collected by NASA, according to new research.
A 2017 study concluded that ancient grass fires had caused the glass's formation, but new research suggests that the glass formed as a result of a cometary explosion close to the desert's surface.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| Scientists have long sought to determine the origin of glass in Chile's Atacama Desert. |
|
| A 2017 study concluded that ancient grass fires had melted the area's sandy soil into glass. |
|
| In 2021, a different study revealed that the mineral signatures of glass samples were consistent with the mineral signatures of comet samples collected by NASA. |
|
| That study concluded that the glass had formed as a result of a cometary explosion close to the desert's surface. |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: Scientific understanding of Atacama Desert glass formation has shifted from attributing it to grass fires (2017) to comet explosions (2021).
Argument Flow: The notes establish a long-standing scientific question, then present two different explanations that emerged from studies four years apart. The 2017 study attributed the glass to grass fires, while the 2021 study, using mineral signature analysis, concluded the glass resulted from a comet explosion.
Step 2: Interpret the Question Precisely
What's being asked? The student wants to describe how scientific understanding about the glass's origin has evolved.
What type of answer do we need? A statement that shows the progression or change in scientific understanding over time.
Any limiting keywords? evolved means we need to show change/development, not just present information.
Step 3: Prethink the Answer
The right answer should:
- Show there was an earlier explanation (2017 grass fires study)
- Show there's a newer, different explanation (2021 comet explosion study)
- Make clear that understanding has changed from one to the other
Scientists have long sought to determine the origin of the glass, with one study concluding that it formed when ancient grass fires melted the area's sandy soil.
- Only mentions the 2017 grass fires study
- Doesn't show any evolution or change in understanding
- Missing the 2021 research entirely
Studies in 2017 and 2021 offered different explanations for the origin of the glass.
- Says there were different explanations but doesn't specify what they were
- Too vague and doesn't actually describe the evolution
Mineral signatures of glass samples are consistent with those of comet samples collected by NASA, according to new research.
- Only focuses on the 2021 findings about mineral signatures
- Doesn't show the evolution from previous understanding
A 2017 study concluded that ancient grass fires had caused the glass's formation, but new research suggests that the glass formed as a result of a cometary explosion close to the desert's surface.
- Shows both the 2017 explanation (grass fires) and the contrasting 2021 explanation (comet explosion)
- Uses transitional language to clearly indicate the shift in understanding
- Perfectly captures how scientific understanding evolved from one explanation to another