Reading Comprehension · Science
PrepTest 115 · Section 3 · Passage 3
Questions 17–23
Before you start
Open PrepTest 115, Section 3 in your official copy from LSAC and read the passage for Questions 17–23, using the structure guide below. The passage is not reprinted here.
Structure guide
- P1: introduces a long-accepted theory and one key assumption inside it, explained with a simple everyday comparison
- P2: describes the biggest challenge: a special test setup, what the theory predicted, and a careful result that flatly contradicted it
- P3: a scientist from inside the old camp drops the key assumption and offers a strange new picture (a second version of the same comparison) that fits the data; the community is critical at first, partly because no explanation came with it
- P4: other researchers supply the missing justification and evidence; the author closes by noting how a crisis turned into a lasting new view
Step 2 · The kid passage
The Ramp Rule and the Tiny Book Disaster
For years, the Reading Club at Maple Street School trusted the Ramp Rule. It said reading points climb smoothly as you read, like walking up a ramp where you can stop at any spot you like. So any score was possible, even 3.27.
The Ramp Rule's big test came from tiny books. A fair test needed a sealed log, a notebook nobody else could touch, so the club could trust that every point came from the reader's own pages and not from points copied over from a friend's chart. Using the Ramp Rule, the club predicted that tiny books would pile up lots of points fast. Lulu kept the log. Tiny books earned almost nothing. The club named it the Tiny Book Disaster.
Priya, who had helped build the Ramp Rule in the first place, then made an odd suggestion. Points do not climb like a ramp, she said. They climb like a staircase: you stand on one step or the next, never in between. Her staircase numbers matched Lulu's log perfectly. Still, the club grumbled at first, partly because Priya could not say why points would come in steps.
A week later, Nadia and Owen found the reason. The reading stamp only lands at the end of a whole chapter, and a book shorter than one chapter gets no stamp at all. Owen later opened the stamp box and confirmed it. So in a few weeks, a disaster turned into the Staircase Rule, which the club still uses.
Step 4 · The courtroom tale
The Case of the Stubborn Scale
In the made-up town of Pebbleford, a spice shop landed in court. Everyone had long assumed its brass scale slid smoothly, so it could show any weight at all. Then an inspector tested it with spotless empty pans, so nothing else could tip the reading. For tiny pinches, it showed almost nothing. Mr. Whitfield, who once helped write the town's scale guide, snapped his suspenders. "Your Honor, this scale moves in notches, not slides." His notch numbers matched the inspector's chart exactly. The judge frowned. "Why notches?" Mr. Whitfield had no answer yet. A week later, a repair expert opened the scale and found a toothed gear, plus a smallest pinch below which it never budged. The judge nodded. "So the puzzle gave us a better guide."