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Making Sense of Scientific Details

Detail problems on the ACT Science Test ask about all the tiny pieces of information that make up an ACT Science passage. There are so many strange vocabulary words, odd data formats, and experiments to keep track of that it can be difficult to remember most of the passage once you’ve finished reading.

Don’t try!  Instead, gather the main gist on the first read, marking up the passage as needed, then simply go back and scan to locate the relevant details. Put your finger on the important detail when you’ve found it, and then eliminate the incorrect answer choices. Writing short notes in the test booklet is also encouraged.



Let’s look a sample passage with lots of details!

Passage I

Although there is good evidence that rivers and even lakes temporarily existed on Mars when that planet was much younger, astronomers are still debating whether a temporary ocean ever existed in a large depression in the northern plains. Two scientists discuss the evidence for an ocean.

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Scientist 1

Satellite data show a feature that resembles some of the shorelines surrounding Earth’s oceans: a terrace, “Shoreline A,” that is almost always at the same elevation wherever it is visible.  There are also three more features that resemble features found in some of Earth’s oceans:

First, there is some evidence for additional terraces at other elevations (representing earlier or later times when the sea level was at that higher or lower elevation for a long period of time).

Second, the surface is much smoother inside Shoreline A than outside the shoreline, exactly as is the case in Earth’s present oceans.

Third, there are features resembling river channels leading into the depression.

Scientist 2

In a few locations (near the Tharsis and Elysium volcanoes, and also near the Lyot crater), the elevation of the proposed Shoreline A is much higher than elsewhere.  The situation is much worse for some of the other potential shorelines – The largest, “Shoreline B,” obviously cannot correspond to the boundary of an ancient ocean because its elevation varies by several kilometers from one end to the other.  The surface of any body of water will, of course, be level – so its shore must also be at the same height at every point.

Even without looking at the questions yet, we can see there is a lot of tiny detail here! Don’t feel the need to understand everything. The question will tell us where to look for the correct answer. Now let’s look at one:

According to the passage, an ocean must have:

  1. A surface that is at the same elevation at all points
  2. A bottom that is at the same elevations at all points
  3. A depth that is the same at different points
  4. A depth that is different at different points



Ask yourself: where was ocean requirements discussed? Scientist 2 talked about why something couldn’t be a shoreline, so let’s look back to that paragraph and search for the criteria he used to draw his conclusion. As Scientist B stated, the surface of any body of water (including an ocean) must be level. He said Shoreline B couldn’t correspond because of the specific detail, “elevation varies.” A level surface is a surface whose elevation is the same at all points. The answer to this Details question is (A).


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