Logical Reasoning · Weaken

PrepTest 144 · Section 4 · Question 21

Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.

Step 1 · Pre-Question Guidance · read this first

Question type

Weaken

The one idea it tests

When a group improves after an activity, something else they did at the same time may be the real cause.

The basic logic

The patty: kids who finished an activity later did better at other things. The top bun: the activity's skills caused it. That is a Rooster move. Pop the argument with another cause that touched the same kids in the same period.

Tiny words that decide it

“likely”
“contribute”
“most”

Playground logic

Marcus's patty: kids who finished juggling club got better at spelling. His top bun: juggling builds focus that helps spelling. Priya pops it with a rival cause: the club met in the library, where those same kids got free spelling help.

Step 2 · The kid story

Juggling and Spelling

Ms. Rivera ran a small juggling club after lunch. Most of the kids who finished the club scored much higher on their next spelling tests. Marcus slaps the desk. "Case closed! Juggling trains your brain to focus, so it helps spelling too!" Priya sips her juice box. "Where did the club meet?" "In the library," Marcus says. "Because the gym was full." Priya points to a sign on the library door: FREE SPELLING HELP, EVERY DAY AT LUNCH. "The juggling kids sat next to the spelling tutor every day," she says. "Maybe the tutor did it, not the juggling balls." Lulu writes on her clipboard: 'Rooster alert. Something else happened to the same kids at the same time.' Kevin adds that dinosaurs could not juggle anyway.

Step 3 · Try the model question

Most kids who finished the juggling club soon scored much higher on spelling tests. So the focus that juggling builds likely helps kids with other schoolwork too.

Suppose each choice is true. Which one most seriously weakens Marcus's argument?

Step 4 · The courtroom tale

The Case of the Marching Band Grades

A school claims its marching band raises grades. Mr. Whitfield reads the evidence: most students who finished a year of band earned higher grades afterward. "So marching makes minds sharper, Your Honor." The other lawyer, Mr. Kim, rises. "Your Honor, band members who want to march in the big parade must keep a B average. That rule pushed them to study harder." The judge raises an eyebrow. "So the grades may come from the parade rule, not from the music?" Mr. Kim nods. "Exactly. A second cause sat right in the same room." Mr. Whitfield loosens his suspenders. "I may need more evidence."

Step 5 · Work the real question

Open PrepTest 144, Section 4, Question 21 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Name the burger: a group finished an activity, then improved at something else, so the activity caused it. Recognize the Rooster. Look for a choice that hands the same group a different reason to improve during the same period. Skip choices about people outside the group unless they truly change the comparison, and skip ones about skill at the activity itself. The best weakener gives a rival cause.