Learn about interesting educational concepts, with a focus on curious or unexpected topics across math and science.

You will find simple explanations and examples for each concept, for all ages and levels of education to engage with. Some concepts may also be helpful for solving brain teasers and puzzles in our collection.

## Guides to Brain Teasers and Puzzles

**Guide to Brain Teaser Interview Questions**

Learn why brain teasers might be asked at an interview, how to prepare for them, and how to ace the brain teaser at the interview itself.

**Guide to Rebus Puzzles**

How to solve rebus puzzles – fun word puzzles in which a common phrase is represented visually in creative ways.

## Basic and Intermediate Math

Fun math concepts and tools, suitable for varying degrees of math knowledge.

**The Pigeonhole Principle**

A simple mathematical concept of having too many items to have only one in each box – which can be applied to solve a surprising number of problems.

**Divisibility Rules**

Shortcuts for determining if a big number is evenly divisible by some common numbers.

**Friedman Numbers**

Numbers that can be written as an expression of their own digits, which make for fun puzzles for all ages.

## Probability and Statistics

Statistics quirks and interesting misuses or misinterpretations, most suitable for those with some high school probability/statistics knowledge.

**The Base Rate Fallacy**

A common fallacy of favoring specific information over base rates, which misleads us into thinking a probability is much higher than it actually is – with serious real-world implications.

**Simpson’s Paradox**

A phenomenon in statistics and probability in which a trend observed in two separate groups is found to be reversed when the groups are simply combined!

**Berkson’s Paradox**

Every statistician knows to be careful about selection bias. Berkson’s Paradox refers to drawing incorrect conclusions due to a particular type of selection bias that results from sampling based on a combination of characteristics.