The learning path
A dozen ways
to meet π.
Short, visual lessons that turn a famous number into a familiar idea. Begin anywhere, or follow the path from the very first circle.
What is π, really?
Meet the ratio hiding in every circle, no matter how big or small.
Begin lesson →A number with a past
From ancient Babylon to modern supercomputers, follow π through time.
Open lesson →π in the wild
See this constant at work in waves, space, sound, and the shape of things.
Open lesson →The circle's secret ratio
Measure a few round things and discover why the answer always comes back the same.
Open lesson →Why the digits never end
Get to know irrational numbers and the wonderfully unfinished nature of π.
Open lesson →Random, but not quite
Explore the patterns and surprises hiding among π's endlessly unfolding digits.
Open lesson →A day for π
How a date on the calendar became a worldwide celebration of circles and curiosity.
Open lesson →Remember a little more
Learn a simple memory journey for carrying your first ten digits with you.
Open lesson →