Logical ReasoningDifficulty: Medium

PT138 S4 Q14 Explanation

Editorial: A proposed new law

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsNecessary Assumption

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Stimulus

Editorial: A proposed new law would limit elementary school class sizes to a maximum of 20 students. Most parents support this measure and argue that making classes smaller allows teachers to devote more time to each student, with the result that students become more engaged in the learning process. However, researchers who the amount of time teachers spent individually with students, the students' average grades were unchanged.

What this question is testing

Necessary Assumption

Your task

Find the assumption the argument requires in order for its conclusion to hold.

Common trap

Answers that would help the argument but aren't strictly required (sufficient, not necessary).

Winning move

Negate each choice — the right one breaks the argument when negated.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
14.

Which one of the following is an assumption required by the

Answer choices

  1. Too Strong: only1% picked this

    The only schools appropriate for study are large

    This is far from our predicted missing link. It doesn't involve connecting "grades" to "engagement in the learning process". Would it hurt this author's argument if we negated this and said, "Sometimes schools other than large elementary school are appropriate for study"? Of course not. Everyone in the world believes that sometimes it would be appropriate to study schools other than large elementary schools.

  2. Too Strong: generally / same / each14% picked this

    Teachers generally devote the same amount of individualized attention to each student

    This is an incredibly strong claim that no one in the real world would assent to: 51% or more of teachers devote an identical amount of personalized attention to every single student in class. Our author certainly didn't commit to such an extreme idea, and if we negated this and said, "Sorry, author, at most 49% of teachers give identical attention to every student", it wouldn't hurt the author in the slightest.

  3. Out of Scope: fewer teachers2% picked this

    Reductions in class size would also involve a decrease in the

    This author never said anything insinuating that reducing class size necessarily brings with it a reduction in the number of teachers. The author is looking at a study where smaller class size went with (presumably) same number of teachers. Because the ratio of students per teacher improved, the teachers could spend more time with individual students.

  4. Correct79% picked this

    Degree of student engagement in the learning process correlates well with

    Why this is right

    This is addressing the big gap between the premise, "we reduced class size, but the grades didn't change" and the conclusion, "reducing class size doesn't lead to students' becoming more engaged in the learning process". The author must think that "grades change" is connected to "engagement in the learning process". If we negated this answer we would get this objection: "yo, author, the degree to which students are engaged in the learning process is not well reflected by grades. So even if grades remained unchanged when that school reduced class sizes, it still may be that engagement in the learning process was changed."

    Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

  5. Too Strong4% picked this

    Parental support for the proposed law rests solely on expectations of increased student engagement in

    Too Strong: solely Only Thing Mentioned ? Only Thing Necessary Assumption answers love to write this style of trap answer, which one might call the All Lives Matter trap answer. When someone says "Black lives matter", they are only affirming that yes, black lives matter. They aren't saying only Black lives matter. Just because black lives are the only ones mentioned doesn't mean they're the only things to which "lives matter" applies. Similarly, when we are told "parents support this measure and argue that students would become more engaged in the learning process", we can't hear that as "they only support it because they think students will become more engaged."

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