The inspiration for this site came from John Allen Paulos' book Innumeracy. From it Fawn Nguyen took the mathematical fun facts, etc. and created middle school mathematics critical thinking problems that relate to ratios and proportional reasoning and require students to compare stuff and really get them thinking.

Here's an example:
Tortoises have the longest lifespan among vertebrates, about 200 years.

A fruit fly's lifespan is about 45 days.
​
If we scaled both lifespans down so that a tortoise's 200 years is now 1 day, then what is the fruit fly's lifespan, in seconds?

Play with objects on a teeter totter to learn about balance. Test what you've learned by trying the Balance Challenge game.

This article attempts to declutter proportionality by having students think about varying quantities and to investigate patterns so they can describe quantities in terms of proportional relationships. Students encounter proportional relationships in their everyday world, and the article provides examples of where these relationships surface and how we can approach building strong ways of thinking. The power of modeling with mathematics is highlighted.