Logical Reasoning · Weaken
PrepTest 140 · Section 1 · Question 13
Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.
Step 1 · Pre-Question Guidance · read this first
- “should not”
- “but”
- “only”
Playground logic
Ms. Rivera blames the glitter in glitter-gel pens for cramps and messy notebooks, since pencil users were fine. But the pencil kids weren't using pens at all. If pens of any kind are unusual for these kids, the pen itself, not the glitter, could be the culprit, and the argument pops.
Step 2 · The kid story
The Glitter-Gel Ban
Ms. Rivera made an announcement. "No more glitter-gel pens in class. For a month, kids who wrote with glitter-gel pens got hand cramps and smudgy notebooks. Kids who used their normal pencils did not." Marcus nodded hard. "Case closed. Glitter is evil." Priya raised her juice box like a hand. "Wait. Do any of us usually write with pens?" Everyone shook their heads. Third grade was a pencil grade. "So," Priya said, "the glitter kids switched from pencils to pens. The pencil kids did not switch at all. Maybe any pen would give us cramps and smudges, glitter or not." Ms. Rivera paused. "So I tested pens, not glitter." Lulu wrote: the comparison group skipped the whole item.
Step 3 · Try the model question
Glitter-gel pens should be banned from class. For a month, students using glitter-gel pens developed hand cramps and smudgy notebooks, whereas students using their usual pencils did not.
Suppose each choice were true. Which one does the most damage to the argument?
Step 4 · The courtroom tale
The Case of the Bouncy Sneakers
Lawyer Grimsby pounded the table. "Your Honor, bouncy-sole sneakers should be pulled from gym class. Students who wore them for a month got sore ankles and blisters, whereas students in their usual sandals did not." Mr. Whitfield rose and smoothed his suspenders. "One question for the coach. Do these students normally wear sneakers at all?" The coach shook his head. "Never. It is a sandals school." Mr. Whitfield turned to the bench. "Then, Your Honor, these students switched to sneakers of any kind. The bounce may be innocent. The sneakers themselves may be the blister makers." Judge Tran crossed out a line in her notes.
Step 5 · Work the real question
Open PrepTest 140, Section 1, Question 13 in your official copy from LSAC (for example in LawHub) and read it there.
Your answer
How to apply it
Find the top bun: a special feature is to blame. Then compare the two groups in the study: list every way they differed, not just the feature named. Look for a choice revealing that the test group received something more basic that the comparison group never got. That gives a rival cause. Skip choices about timing details or missing explanations unless they truly create a rival.