Reading Comprehension · Science
PrepTest 121 · Section 2 · Passage 3
Questions 13–19
Before you start
Open PrepTest 121, Section 2 in your official copy from LSAC and read the passage for Questions 13–19, using the structure guide below. The passage is not reprinted here.
Structure guide
- P1: states an accepted background theory, then lays out a long-standing puzzle (something is missing) and the placeholder idea experts propose to fill it
- P2: asks what the placeholder could be, names one favored candidate, and explains the old assumption that would rule it out
- P3: reports new evidence that knocks down that assumption, describing how a test confirmed it and gave a rough estimate
- P4: weighs the result: the candidate covers only part of the gap, yet the author says that still matters, and some experts are optimistic
Step 2 · The kid passage
The Case of the Extra Water
Everyone agrees plants grow only with water, and more water means bigger plants. But Priya's garden club is puzzled: the class watering log shows less than a third of the water the tomato rows would need to grow as tall and tangled as they are. So the club guesses that plain, ordinary watering nobody wrote down, nicknamed "secret sprinkles," keeps the rows going.
Who could the secret sprinklers be? Kids have suggested raccoons, even the principal. The best guess is the kindergartners, because they surely exist and are the biggest group at school. The trouble is that everyone has assumed kindergartners carry no watering cans. If so, they are out: no can, no water, and without water, the rows cannot flourish.
But Lulu found fresh evidence that they do. On her clipboard she tracked three recess jobs: weeding, digging, and the splash squad. Kids switch between jobs, and the garden rule says you may join the splash squad only if you hold a can. She even handed one weeder a sign-up card and watched him join the splash squad later. She figured each kindergartner pours between a spoonful and a cupful a day.
Not much per kid, but so many kindergartners add up, especially since everyone thought they poured nothing. Still, even the biggest guess covers only about a quarter of the missing water. Even so, that changes how the club sees the garden. Some members call it the best answer yet and plan to check the first graders next.
Step 4 · The courtroom tale
The Bookshop With Too Many Empty Shelves
Mr. Whitfield snapped his suspenders. "Your Honor, this bookshop ships out four times more books than its register shows. Something else must be selling them." The judge frowned. "Like what?" "The cafe counter," said Mr. Whitfield. "It exists, and it serves more customers than any part of the shop. Everyone assumed it had no scanner, and without a scanner it cannot sell a book." "But these receipts show customers switching between the coffee menu, the snack menu, and the book menu. The book menu works only with a scanner. So it has one." The judge did the math. "That covers a quarter of the gap at most." "True," said Mr. Whitfield, "but a quarter is a real dent, and now we know where to look next."