Drill 5 · Reading & Writing · Hard Command of Evidence
SAT Reading & Writing: Hard Command of Evidence (Drill 5) is a Reading & Writing practice drill covering Hard Command of Evidence. It contains 5 original questions created by Brian Stewart, a Barron's test prep author with over 20 years of tutoring experience.
Five hard Command of Evidence questions drawing on new findings, a graph, a table, and a classic short story. Each wrong choice is plausible but either covers only half the claim or runs the wrong direction. Decide what the evidence must show, then find the choice that shows all of it.
Engineers developed a clear coating for bridge cables that lasts far longer than the standard coating in coastal areas. They proposed that the new coating works by blocking salt from reaching the metal, since salt is what drives the corrosion that destroys cables. A skeptic suggested the new coating might simply be physically tougher, resisting scrapes and weather better, with salt having nothing to do with its advantage.
Question 1. Which finding, if true, would most directly support the engineers' proposal?
Explanation: Choice A is the best answer because the proposal is that the coating helps specifically by blocking salt, so the evidence must show its advantage depends on salt being present. The two coatings lasting equally long inland, where there is little salt, shows the new coating only pulls ahead where salt is present, which points to salt-blocking as the mechanism. Choice B is wrong because using the same application equipment is a practical detail unrelated to why the coating lasts longer. Choice C is wrong because the coating being slightly thicker would fit the rival toughness explanation as easily as the salt one, so it does not single out the mechanism. Choice D is wrong because more frequent inspection of coastal bridges is background about coastal conditions, not evidence about the coating's mechanism.
Oceanographers measured dissolved oxygen at increasing depths at two sites: an open-sea site and an enclosed bay with limited water exchange. They concluded that the enclosed bay loses oxygen with depth far faster than the open sea, reasoning that poor mixing in the bay lets deep water become starved of oxygen. They needed the data to show not just that oxygen falls with depth, but that it falls much more steeply in the bay.
Question 2. Which choice best describes data from the graph that support the oceanographers' conclusion?
Explanation: Choice C is the best answer because the conclusion compares how fast oxygen falls with depth at the two sites, so the evidence must contrast the two slopes. The graph shows the open-sea line easing down only from about 9 to about 7 across the depth range, while the bay line plunges from about 9 to under 1, a far steeper drop, the contrast the claim rests on. Choice A is wrong because both sites being highest at the surface is true but says nothing about how steeply oxygen falls with depth. Choice B is wrong because a single 50-meter comparison shows the bay is lower at one depth but not that it declines more steeply across depth. Choice D is wrong because describing only the open-sea site's deepest value never sets the two slopes side by side, which is the whole point.
Young songbirds of a certain species sing a complex song as adults. Researchers observed that nestlings hear adult males singing for weeks before they themselves can sing, and concluded that the young birds learn the song by listening to and copying nearby adults. They proposed that exposure to adult song is what allows the young to develop the correct adult song.
Question 3. Which finding, if true, would most directly weaken the researchers' conclusion?
Explanation: Choice B is the best answer because the conclusion is that the young learn the song by hearing adults, so birds raised in soundproof isolation that never hear an adult yet still develop the normal song show the song does not depend on that exposure, undercutting the learning explanation. Choice A is wrong because birds that could still hear adults developed the normal song, which is consistent with learning by listening; removing only sight does not test whether hearing the adults is necessary, so it does not weaken the claim. Choice C is wrong because when adults sing most intensely is a side detail that does not test whether exposure is necessary. Choice D is wrong because the adult song having more notes than nestling calls does not address whether the young learn it from adults.
Average Test-Score Gain (points) by Support Type and Starting Level
| Starting level | Extra class time | One-on-one tutoring |
|---|---|---|
| Lowest third | 6 | 15 |
| Middle third | 9 | 11 |
| Top third | 10 | 8 |
A school compared two kinds of extra support by measuring the average score gain each produced for students grouped by starting level. The principal wanted to know for which students tutoring was the clearly better choice rather than simply adding class time. The data show that tutoring outpaced extra class time by the widest margin for ________
Question 4. Which choice most effectively uses data from the table to complete the statement?
Explanation: Choice D is the best answer because the statement asks where tutoring beat extra class time by the widest margin. The tutoring advantage is 9 points for the lowest third, 15 against 6, but only 2 points for the middle third and negative for the top third, so the lowest third is where tutoring most clearly wins. Choice A is wrong because the top third's tutoring gain of 8 is its smallest, but the question asks about the margin over class time, not the raw gain. Choice B is wrong because the middle third shows tutoring only slightly ahead, a narrow margin, not the widest. Choice C is wrong because the top third is the one group where class time beat tutoring, the opposite of the widest tutoring margin.
"A Scandal in Bohemia" is an 1891 story by Arthur Conan Doyle, narrated by Dr. Watson. Early in the story, Watson explains why Holmes avoided strong feeling. In Watson's account, the danger of emotion for Holmes was not that it was unbecoming but that it would actively disrupt the precise reasoning he depended on, throwing his conclusions into doubt: ________
Question 5. Which quotation from "A Scandal in Bohemia" most effectively illustrates the claim?
Explanation: Choice A is the best answer because the claim is specifically that emotion would corrupt Holmes's reasoning, and asks for the quotation that illustrates it. The keyed excerpt compares a strong emotion to grit in a sensitive instrument or a crack in a lens, images of something that actively distorts a precision tool, which illustrates emotion disrupting his reasoning. Choice B is wrong because this says the softer passions are useful things to observe in other people, which is about studying others, not about emotion disrupting Holmes's own reasoning. Choice C is wrong because praising him as a perfect reasoning machine describes his skill, not the threat emotion posed to it. Choice D is wrong because calling emotions abhorrent to his balanced mind shows his distaste but not that emotion would throw off his reasoning.