Doubling

Each step makes twice as many: 2, 4, 8, 16. It grows faster than anyone expects.

Through 7 doors: Chess, Computers, Martial arts, Paper folding, Photography, Saving up, Singing.

By age

Ages 3–5 Not made yet.
Ages 6–8
- Five Lights (Computers)
- Half of a half (Paper folding)
Ages 9–14
- Grains on a Chessboard (Chess)
- Reading a Bracket (Martial arts)
- Seven folds? (Paper folding)
- One Stop, Twice the Light (Photography)
- Compound Growth (Saving up)
- The Rule of 72 (Saving up)
- An Octave Doubles (Singing)
Ages 15–18
- Why there is no shortcut (Paper folding)
- Time Multiplies (Saving up)

Meeting one idea in a second world is where it starts to belong to you, not to the world you met it in. These pages are a design, not a promise.