DROP D
one string down · everything else unchanged
Free
HALF STEP DOWN
every string down a semitone · same shapes
Free
OPEN C
the deepest of the open tunings
Free
OPEN D
the open strings are already D major
Free
OPEN G
the open strings are already G major
Free
MAMMALS IN TIME
from the first synapsid to us · 320 million years on one axis
Free
VERTEBRATES IN TIME
when each group appeared · five hundred million years on one axis
Free
BASIC PHYSICS FORMULAS
fifteen formulas · every letter explained beneath it
Free
ANIMALS
the main branches — from comb jellies to chordates · who is actually related to whom
Free
VERTEBRATES
from lamprey to bird · and why "fish" and "reptiles" are not groups
Free
MORSE CODE
26 letters and 10 digits · dot, dash
Free
THE BASKETBALL
four FIBA sizes with their circumference and mass — and why the rules set a bounce, not a pressure
Free