Question 150·Hard·Central Ideas and Details
Citizen science projects that enlist volunteers to document local biodiversity have flourished in recent years. Professional ecologists applaud the extensive geographic coverage these projects provide, yet they remain concerned about data accuracy. Comparative studies of bird inventories show that volunteers frequently misidentify rare species but record common ones with notable completeness. To curb such errors, many platforms now request photographic evidence or automatically flag unusual sightings for expert review. Although these measures slow data processing, they markedly improve reliability. Consequently, citizen science can play a significant role in ecological research when precautions are taken to balance data breadth with precision.
Which choice best states the main idea of the passage?
For main idea questions, quickly identify the topic (who/what the passage is about) from the first sentence, then read the last sentence carefully because it often states the author’s conclusion. As you skim the middle, note any repeated themes (such as benefits vs. drawbacks). Before looking at the choices, sum up the main point in your own words in 1 short sentence. Then eliminate answer choices that are too extreme, focus on minor details, or ignore part of the passage’s reasoning (for example, mentioning only problems but not solutions). Choose the option that best matches your own summary and covers the full scope of the passage’s argument.
Hints
Locate the topic and the conclusion
Reread the first and last sentences. What kind of projects are being discussed, and what does the author ultimately say they can do?
Evaluate the author’s attitude
Ask yourself: does the author think citizen science is mostly useless, mostly helpful, or helpful only under certain conditions? Look for words that signal approval or concern.
Focus on repeated key ideas
Notice which ideas appear more than once (for example, about coverage or accuracy). The main idea should bring together the major strengths and concerns, not just one detail.
Watch out for extremes
Be cautious of answer choices that use strong words like "only," "little confidence," or imply that the data are "largely unreliable." Do those match the balanced tone of the passage?
Step-by-step Explanation
Identify the overall topic and focus
Read the first couple of sentences to see what the passage is about:
- It introduces citizen science projects with volunteers documenting biodiversity.
- It notes that professional ecologists like the extensive geographic coverage but worry about data accuracy.
So the passage is mainly about how useful citizen science data are and what affects their reliability.
Notice the problem and the response to it
Look at the middle of the passage:
- Comparative studies show volunteers often misidentify rare species but are good at recording common ones.
- To reduce errors, platforms now request photos or flag unusual sightings for expert review.
- These steps slow processing but "markedly improve reliability."
The author is explaining both the limitations (errors, slower processing) and the solutions (added checks that improve reliability).
Find the author’s final conclusion
The last sentence often states or clarifies the main idea:
"Consequently, citizen science can play a significant role in ecological research when precautions are taken to balance data breadth with precision."
This tells you the author’s main claim:
- Citizen science can be important for ecological research.
- This depends on precautions that balance broad coverage (data breadth) with accuracy (precision).
Any correct answer must reflect both the value of wide coverage and the idea that proper controls make the data reliable enough to use.
Match the conclusion to the best answer choice
Now compare each option with that conclusion:
- Eliminate choices that say citizen science is mostly unreliable or that ecologists have little confidence in it.
- Eliminate choices that overstate details, like saying there is only one way to ensure accuracy or that photos are required for every observation.
Choice B accurately reflects the passage’s main point: that citizen science is valuable because of its wide geographic coverage and, when appropriate accuracy checks are in place, it can provide dependable data for ecologists.