I know many of you are fans of the web comic "XKCD". They have an interesting new feature called "What If" described as "Answering your hypothetical questions with physics, every Tuesday." http://what-if.xkcd.com/1/
The first few questions are:
* What would happen if you tried to hit a baseball pitched at 90% the speed of light?
* What if everyone who took the SAT guessed on every multiple-choice question? How many perfect scores would there be?
* How much Force power can Yoda output?
* What would happen if you were to gather a mole(unit of measurement) of moles (the small furry critter) in one place?
The answers actually go into fair depth, showing imagination and critical thinking skill.