How an IQ Test Can Help Avoid Trap Answers on the ACT

Published on Tuesday, February 26th, 2019 by

ACT Chalk Talk #14


Students who approach the ACT with a careful mindset avoid trap answers and make less mistakes. But how can you teach them to approach the test differently? Give them the three question IQ test!

  1. A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?
  2. If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?
  3. In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake?

These three questions make up the Cognitive Reflection Test (CRT). High-performing students at Harvard, Yale, and other top universities were given the CRT, and only 17% of participants earned a perfect score. Go ahead—take the test and see how you do. The answers are at the bottom of this post as well as the common trap answers.

How to Beat the CRT

The key to doing well on the CRT is to avoid the intuitive choice and engage your analytical reasoning skills. This is a slower, more methodical thought process. It’s the same thought process that increases success on the ACT.

Analytical Reasoning Is Key

When researchers gave college students the CRT in a hard-to-read font, scores went up significantly. Why? Because it forced students into a more careful frame of mind. In other words, squinting boosts your score!

Trap Answers on the ACT

Just because an answer feels right doesn’t mean it is right. The test writers design trap answers to catch students in mistakes. For example, students will see a choice on the Math test that matches a number from just the first step in solving the problem, or a positive number when a negative one is needed. Likewise, in English, a comma might appear in a place where students would naturally pause in speech, but no comma is grammatically required.

Slow Down to Up Your Score

On the ACT, if the right answer to a question jumps out to your students, they should immediately react with suspicion and analytically verify their instincts. Is there another choice that is better? Have they made any errors? Have they truly answered the question?

Checking Your Work

Many students have no idea how to effectively check their work. If they have time left on a test, they typically waste it. These are often the same students who rest their heads on their desks after their bubble sheets are filled in. It’s worth the time to teach students how to verify their work (more on this in an upcoming post).

Correct Answers

1) $0.05. (The bat costs a dollar more: $1.05. Together the bat and ball cost $1.05 + $0.05 = $1.10.)

2) 5 minutes. (We are asked to produce 20 times the number of widgets, but we are provided 20 times more machines, so it will take the same amount of time.)

3) 47 days. (Since the surface area doubles each day, if the lake was covered at day 48, then it must have been halfway covered the day before.)

Trap Answers

1) $0.10. (You get this answer when you subtract $1.00 from $1.10. But if the ball is $0.10 and the bat is $1.10, then the total cost is $1.20, which won’t work.)

2) 100 minutes. (You get this answer if you match the pattern of the changes from 5 to 100.)

3) 24 days. (24 days is half the number of days, but that doesn’t give you half the surface area.)