Read an Academic Passage — what evidence can show
Read an Academic Passage: evidence and explanation
This is an original, site-created TOEFL-style Read an Academic Passage drill, not an ETS question. ETS describes this task as a short expository passage of about 200 words followed by five questions. Read the passage and answer the five checks before using the worked notes below. All the information you need is in the text.
What can a courtyard comparison show?
At the fictional Lydon College, students asked whether shade alone could cool the air in a courtyard. They put identical thermometers at the same height in two spaces, one with trees and grass and one with bare brick. At noon on eight dry days, the greener courtyard averaged three degrees cooler. But this result could not isolate the effect of shade. The spaces also differed in ground cover, airflow and how much water their surfaces held.A ninth day brought rain, and the temperature gap became smaller. The students did not take this as proof that rain removed the effect of trees: clouds, wet surfaces and wind had changed together. Instead, they compared two halves of the same brick courtyard. A removable cloth shaded one half; the ground surface remained brick on both sides. They switched the thermometers' positions each day in case one device read consistently high. Over six dry afternoons, the shaded half averaged one degree cooler.
The second test supports a limited claim: shade contributed to cooler air there under those conditions. It does not show that trees would have exactly the same effect, since cloth and trees differ in other ways. Nor does it establish that people felt more comfortable; nobody was asked. A better comparison narrows an explanation without settling every consequence.
The thermometers took measurements, not sides in an argument.
What was observed on the first eight dry days?
The passage says the greener courtyard averaged three degrees cooler at noon on eight dry days. The one-degree cloth result belongs to the later test.
In the passage, what does 'isolate the effect of shade' mean?
Trees, grass, brick and airflow differed together; the first comparison could not separate the effect of shade from these other factors.
Why did the students test shade cloth within the same brick courtyard?
The passage states that both halves stayed brick while one gained shade. This removes one difference that complicated the first comparison.
How does the rainy ninth day relate to the first eight days?
The gap became smaller, but clouds, wet surfaces and wind changed together. The observation qualifies the pattern without proving which change caused it.
Why does the writer mention that nobody was asked about comfort?
The second test measured air temperature, not human experience. The sentence prevents readers from treating a cooler reading as proof of greater comfort.
Separate what was observed from what caused it
The first comparison found a difference: the greener courtyard was cooler on eight dry days. It did not show that shade alone caused all three degrees of the difference. Trees, grass, brick and airflow changed together. When several features differ, one observed result cannot assign a precise share to each feature.
The rain day was another observation, not a controlled rain experiment. Because clouds, moisture and wind changed at the same time, a narrower gap cannot be assigned to rain alone. This is the paragraph's reasoning, not specialist climate knowledge.
Notice what the second comparison holds steady
In the second test, both halves are in the brick courtyard, so the ground surface is the same. The removable cloth changes the shade. Switching the thermometers' positions reduces the risk that a warmer-reading device always sits on the same side. The test is more informative about shade than the first, though it still does not recreate everything a tree does.
Observation: under the cloth, the measured air averaged one degree cooler. Reasonable inference: shade contributed to the difference in that place during those six dry afternoons. Overclaim: trees always cool every courtyard by one degree.
Match each question to a sentence or a limit
A detail question points to a measured result. A vocabulary question asks what a word does in this argument: isolate means separating one possible cause from others. An inference question may ask why the researchers changed the design. A purpose question asks why the writer adds a limitation, such as the fact that nobody was asked about comfort.
When reviewing, point to the line that makes the correct option true and the line or missing evidence that makes each attractive wrong option fail. Do not use outside knowledge to strengthen a claim the passage itself keeps narrow.
Task description checked on 23 September 2026: ETS updated TOEFL iBT overview, Academic Passage sample tasks and ETS Reading section.