HANDWASHING
five steps, and the 20 seconds that actually matter
LOGIC GATES
Seven digital-logic symbols — and how to build six of them from a single element, NAND
THE 9 MAJOR FOOD ALLERGENS
the foods US law singles out by name, and the two ways a label is allowed to say so
THE BRAILLE ALPHABET
63 characters of the cell in seven lines — 26 letters, the digits, the punctuation and 8 prefixes
IRREGULAR VERBS
the 100 you meet most: base · past · past participle — grouped by the four patterns, not shuffled alphabetically
LANGUAGE FAMILIES
who is related to whom — on the numerals three and two in twenty-seven languages
LETTER TEAMS
40 letter combinations and the sounds they spell, in IPA, with one example word each
SIGHT WORDS
all 220 Dolch service words in five grade groups, Pre-K through third — with the top of the Fry frequency list up front
DIVISIBILITY TESTS
what to read in a written number instead of dividing it: the tail, the digit sum and composite divisors
LEAP YEARS
one rule, a cycle of four hundred years and the ninety-seven extra days in it
PASCAL’S TRIANGLE
the first thirteen rows, the sum of each row and the pattern of the odd numbers
ROMAN NUMERALS
seven symbols · ones, tens, hundreds · years
THE SOPRANO RECORDER
all 27 notes from C5 to D7 in the Baroque and German systems — and how to tell which one you hold
THE EIGHT BLOOD TYPES
three antigens, eight types — and the one rule the whole table of compatibility follows from
THE TEN CLOUD GENERA
three levels of the troposphere to one scale, and the ten genera that live in them
THE VERTICAL PLANET
from the Challenger Deep to the summit of Everest · one scale, nothing compressed
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 MOHS HARDNESS SCALE
ten reference minerals and five household probes: who scratches whom
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
ROCK CLASSIFICATION
the three classes, 24 named rocks and the cycle that links them — after USGS and NPS
SPECTRAL LINES
five gases on one wavelength scale, from the violet edge to the red
ANIMALS
the main branches — from comb jellies to chordates · who is actually related to whom