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Logic puzzles

A collection of puzzles and brainteasers to challenge your logical thinking skills. Beware: While some of these puzzles are straightforward, but many of them are “mind illusions” - in other words, they have counterintuitive solutions!
What are Mind Illusions?

We’re all familiar with optical illusions. These are images that demonstrate that our eyes can fool us. Traditionally called veridical paradoxes, mind illusions are puzzles or brainteasers that demonstrate that our minds can fool us.

Our intuition is excellent at making fast judgments, but not always for making correct ones. When we make judgments quickly, we can get things wrong. When we have the luxury of time, it is worth thinking about things slowly and carefully before making decisions or drawing conclusions.

Just like we might need a ruler or some other tool to make correct judgments when faced with an optical illusion, we need slow, careful thought to make correct judgments when faced with mind illusions.

The first puzzles are the easiest ones for most people, but even adults frequently get even these ones wrong.

Highly intelligent children tend to have friends who are less intelligent than they are. What is the most likely explanation for this? You post a survey asking, 'Do you like surveys?' 100 people fill out the survey. 95 of them answer 'Yes'. Can you conclude that most people like surveys? Can you solve the baseball puzzle? A ball and a bat together cost $1.10. The bat costs $1 more than the ball. How much does the ball cost? You have four cookies. One of them turns mice pink an hour after they eat even one bite, but you don’t know which one! You need to figure it out in an hour. Can you solve this math puzzle? Look at the picture and determine how much an empty jar weighs. There are multiple ways to solve this. Three smart boys are standing in a line. Each is wearing a hat that is either red or blue, but they don’t know the color of their own hat. You are responsible for choosing where to put shields on new spaceships. From the data given, determine the best place to put the shields. If a card has a vowel on one side, then it has an even number on the other side. Which cards must be flipped to decide if this statement is true? You wrap a band around the equator so that it touches the ground at all places. Then you add 10 meters to its length. How far will it rise above the ground? You are standing at the South Pole. You walk 1 kilometer north. You turn 90 degrees and walk in a line. Will you ever reach the South Pole again? You have 100 kg of potatoes that are 99% water by weight. They dehydrate, and now they are 98% water by weight. How much do they weigh now? You are on a game show. You have to choose between one of three doors. Behind one of them is a car; behind the other two, goats. Can you solve the coin flip puzzle? If you toss a coin 4 times, what is the most likely split between heads and tails? You have 50 red balls and 50 blue balls. You can distribute them between two boxes in any way you choose. Someone will come and pick a box at random, and then pick a ball from that box at random? There are two bags - one with two gold coins, and the other with a gold coin and a silver coin. You choose a bag at random, and pick a coin from that bag. It’s a gold coin! What are the chances you picked from the bag with two gold coins?

Courses

Fallacy Detectors Part 1

Fallacy Detectors Part 1

Develop the skills to tackle logical fallacies through a series of 10 science-fiction videos with activities. Recommended for ages 8 and up.

US$15

A Statistical Odyssey

A Statistical Odyssey

Learn about common mistakes in data analysis with an interactive space adventure. Recommended for ages 12 and up.

US$15

Symbolic Logic for Teens Part 1

Symbolic Logic for Teens Part 1

Learn how to make sense of complicated arguments with 14 video lessons and activities. Recommended for ages 13 and up.

US$15

Emotional Intelligence

Emotional Intelligence

Learn to recognize, understand, and manage your emotions. Designed by child psychologist Ronald Crouch, Ph.D. Recommended for ages 5 and up.

US$15

Worksheets

Symbolic Logic Worksheets

Symbolic Logic Worksheets

Worksheets covering the basics of symbolic logic for children ages 12 and up.

US$5

Elementary School Worksheets and Lesson Plans

Elementary School Worksheets and Lesson Plans

These lesson plans and worksheets teach students in grades 2-5 about superstitions, different perspectives, facts and opinions, the false dilemma fallacy, and probability.

US$10

Middle School Worksheets and Lesson Plans

Middle School Worksheets and Lesson Plans

These lesson plans and worksheets teach students in grades 5-8 about false memories, confirmation bias, Occam's razor, the strawman fallacy, and pareidolia.

US$10

High School Worksheets and Lesson Plans

High School Worksheets and Lesson Plans

These lesson plans and worksheets teach students in grades 8-12 about critical thinking, the appeal to nature fallacy, correlation versus causation, the placebo effect, and weasel words.

US$10

Statistical Shenanigans Worksheets and Lesson Plans

Statistical Shenanigans Worksheets and Lesson Plans

These lesson plans and worksheets teach students in grades 9 and up the statistical principles they need to analyze data rationally.

US$10