Why a hammer and a feather fell together on the Moon.
Illustrated scene · , drop both, then switch the air off
Why Mars sometimes seems to drift backwards.
Orbit view · , let Earth overtake Mars
How Archimedes trapped pi between two polygons.
Compass and ruler · , double the sides and squeeze pi
How one drought reshaped Darwin’s finches’ beaks.
Population model · , run a drought, watch the beaks shift
How Mendeleev left gaps for elements not yet found.
Card table · , sort the elements, predict the gap
How sea otters keep kelp forests standing.
Food web · , take the otters out
Why you don’t notice the hole in your vision.
Body view · , find the blind spot in your own eye
How James Lind tested six scurvy cures in 1747.
Ledger · , compare six treatments side by side
Why Britain skipped 11 days in September 1752.
Calendar wheel · , cut 11 days, realign the calendar
How tree rings can date a beam to a single year.
Timeline · , slide ring patterns until they match
How a grid of signs revealed Linear B was Greek.
Logic grid · , fill a grid of signs and sounds
Why trade pays even when one side is better at both.
Flow diagram · , split the work, follow the trade
Why spaced practice beats cramming in the long run.
Graph · , space your reviews, flatten forgetting
When to stop looking: the 37% rule.
Number line · , slide the cutoff, find the best
How two strangers agree on a secret in public.
Dialogue · , play Alice, Bob and an eavesdropper
Why airliner windows have rounded corners.
Stress field · , watch stress crowd at a corner
How the Pantheon’s dome has stood for 1,900 years.
Cutaway · , slice the dome, weigh each layer
The man hidden under Picasso’s The Blue Room.
Art lens · , scan the canvas layer by layer
How Bach wrote a tune that fits with itself backwards.
Score · , flip the melody, play both
Why Greenland looks as big as Africa on many maps.
Map · , slide Greenland to the equator
How magnetic stripes showed the seafloor spreads.
Map over time · , pull the plates apart, read the stripes
Why the Ship of Theseus has no easy answer.
Argument map · , map each answer and what it costs