DADGAD
D — A — D — G — A — D
DROP D
one string down · everything else unchanged
HALF STEP DOWN
every string down a semitone · same shapes
OPEN C
the deepest of the open tunings
OPEN D
the open strings are already D major
OPEN G
the open strings are already G major
UKULELE CHORDS
the first twelve chords · standard tuning G C E A
THE BEAUFORT SCALE
thirteen forces of wind — from water like a mirror to a wave of fourteen metres
THE EIGHT BLOOD TYPES
three antigens, eight types — and the one rule the whole table of compatibility follows from
RED CABBAGE pH INDICATOR
the purple juice that changes colour: acid or base, without asking a book
THE TEN CLOUD GENERA
three levels of the troposphere to one scale, and the ten genera that live in them
COLOUR GAMUTS
sRGB, Display P3, Rec. 2020 and ProPhoto RGB on the CIE 1931 chromaticity diagram
THE COMPASS ROSE
the sixteen compass points with exact bearings: four cardinal, four intercardinal, eight in between
THE VERTICAL PLANET
from the Challenger Deep to the summit of Everest · one scale, nothing compressed
TN, VA, IPS AND OLED
what differs inside the cell · and a paper describing each mode
MAMMALS IN TIME
from the first synapsid to us · 320 million years on one axis
VERTEBRATES IN TIME
when each group appeared · five hundred million years on one axis
THE FUJITA SCALE
six categories of tornado damage — and the two different winds assigned to them
GREEK LETTERS IN SCIENCE
10 capitals with a shape of their own, 14 twins of Latin letters, and what each one stands for
USDA HARDINESS ZONES
the 13 zones by average annual extreme minimum — each range in °F and °C, with the a and b half-zones
THE MOHS HARDNESS SCALE
ten reference minerals and five household probes: who scratches whom
THE MOMENT MAGNITUDE SCALE
what a single step hides: ×10 in recorded amplitude and roughly ×32 in released energy — drawn to true scale
THE PERIODIC TABLE
all 118 elements: symbol, atomic number and IUPAC atomic weight in every cell — blocks in colour, lanthanoids and actinoids offset below
BASIC PHYSICS FORMULAS
fifteen formulas · every letter explained beneath it
THE ELECTROMAGNETIC SPECTRUM
eighteen decades of frequency · and how much of it the eye sees
PLASTIC RESIN CODES
the seven codes on the bottom of an article per ASTM D7611: which resin each number names and what it means for sorting
RESISTOR COLOUR CODE
the bands, the tolerances and the preferred series of two standards
ROCK CLASSIFICATION
the three classes, 24 named rocks and the cycle that links them — after USGS and NPS
THE SAFFIR-SIMPSON SCALE
five categories of hurricane wind — and how much more damage each next one does
SPECTRAL LINES
five gases on one wavelength scale, from the violet edge to the red
SPEED THRESHOLDS
six thresholds where a different physics begins · every figure computed, not typed
WHAT A TORNADO BREAKS
twenty-eight damage indicators — and the wind at which each one gives way
TORQUE
why the same dumbbell grows heavier as the arm rises, and how to work it out in advance
ANIMALS
the main branches — from comb jellies to chordates · who is actually related to whom
THE TREE OF LIFE
who sits inside whom · where animals, fungi and plants actually are
VERTEBRATES
from lamprey to bird · and why "fish" and "reptiles" are not groups
CROCHET SYMBOLS
the standard chart symbols, abbreviations and US/UK name differences — per the Craft Yarn Council standards
MORSE CODE
26 letters and 10 digits · dot, dash
PHONETIC ALPHABET
the ICAO standard · for radio and telephone
FLAG SEMAPHORE
two flags, eight positions 45 degrees apart — all 26 letters; after the numerals sign A–I read as 1–9 and K as 0
MARITIME SIGNAL FLAGS
the twenty-six alphabet flags of the International Code of Signals — and what each one means alone
NUMERAL PENNANTS AND SUBSTITUTES
how to fly the same flag twice in one group with only one set aboard
THE BASKETBALL
four FIBA sizes with their circumference and mass — and why the rules set a bounce, not a pressure
FOOTBALL: THE BALL
Law 2, three codes of the game, five sizes and three FIFA quality marks — what a ball must survive
BALLS BY THE RULES
eleven sports at true relative size — circumference, mass, pressure, and who sets them
BISHOP
a diagonal at any distance — and the half of the board that will never come
KING
one square in any direction, from three in the corner to eight in the middle, and castling
KNIGHT
the nearest square off the lines, over pieces, and four moves to the square next door