Skip Navigation
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Last three!

Last three!

impossible triangle illusion

Impossible Triangle

arrows are same length

Which is longest?
Actually, the Vertical lines are both the same length.

reversing staircase illusion

Stare at the Reversing Staircase Illusion until it changes to a different staircase.

question marks
Other stuff you might like ...
How sharp is your mind? Try out these fun quizzes and see.
Back to Top