How Your Science Fair Project Prepared You for LSAT Logical Reasoning


Manhattan Prep LSAT Blog - How Your Science Fair Project Prepared You for LSAT Logical Reasoning by Ally Bell

When I was in fourth grade, I designed a bizarre, painful, and deeply flawed experiment for the school science fair. My goal was to test the relative effectiveness of garlic and bug spray for repelling mosquitoes. I sacrificed myself for science and covered one-third of my arm in garlic, one-third in bug spray, and one-third in nothing, then stood outside next to the swampy forest at dusk to tally the bug bites. Even with fake arms hanging off of my project board, dotted with permanent marker “mosquito bites,” I still only took home an honorable mention.

Perhaps you can see why. Take a moment to think about all the flaws in my science experiment. Was the garlic scent mixing with the bug spray scent to create completely indistinguishable effects? How could I generalize from a study conducted on just one foolish nine-year-old to draw conclusions about the population as a whole?

Trust me, the LSAT would also have ripped apart the design of my science experiment. It comes as a surprise to some people that the LSAT Logical Reasoning section likes to test the principles of scientific investigation, but it makes sense: science has a clear system for how we prove things to be true, and in particular for how we prove causation.

So how can we translate our traumatic memories of elementary school science fairs into LSAT Logical Reasoning success? Here are a few familiar concepts to keep in mind as you navigate LSAT Logical Reasoning questions:

Control Groups

Let’s say that you want to prove that driving in the dark causes accidents, so you look at the accident rate between sunset and sunrise for your city. There are 100 accidents every night—that’s pretty high! But you can’t reach any conclusions until you compare it to the number of accidents during the day. What if there are also 100 accidents during the day? Then perhaps the high rate of accidents has nothing to do with whether it’s dark out. That’s what control groups are for—if you want to prove that A causes B, you need to look at what happens when A occurs, but also what happens when A doesn’t occur. That’s why in medical experiments, one group of people is given a type of treatment, while the other is given a placebo. The LSAT often presents arguments that try to establish causality, but fail in part because they don’t offer a control group.

Random, Representative Samples

In clinical trials, scientists also use random, representative samples: they make sure that the people in a treatment group and a control group are randomly selected, and that factors like gender, overall health status, and socioeconomic status are evenly distributed in both groups in a way that represents the broader population. If you tested which brand of pizza was the best by surveying all your family members, your experiment would not pass LSAT muster. Why? Maybe your family has an emotional association with one pizza brand from years of eating that pizza while watching your favorite football team. That’s probably not representative of the population as a whole. LSAT Logical Reasoning likes to create flawed arguments in which conclusions are drawn from non-representative samples.

Drawing Conclusions from Comparisons

Can you predict human behavior by analyzing the behavior of a lab rat? If you’re going to try, you need to make a case that lab rats and humans are similar in all the ways that matter for your particular theory. The LSAT likes to check your understanding of how these comparisons work. Keep an eye out for what similarities and differences would be relevant to the argument at hand.

As you work through your next set of LSAT Logical Reasoning practice problems, keep your eyes open for questions that address conclusions drawn from studies or experiments: some of these issues may be at play! If you find one, be sure to thank your former science teachers.

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Ally Bell is a Manhattan Prep instructor based in San Francisco, CA. Ally first encountered the LSAT while getting her Bachelor of Arts in English and history at Duke University. In college, she scored a 178 and very nearly applied to law school. In the end, she followed her true passion, teaching. As an LSAT teacher, she has the opportunity to blend her love for teaching with her passion for logical argument. Check out Ally’s upcoming LSAT courses here.

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