RED CABBAGE pH INDICATOR
the purple juice that changes colour: acid or base, without asking a book
THE COMPASS ROSE
the sixteen compass points with exact bearings: four cardinal, four intercardinal, eight in between
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
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 MOMENT MAGNITUDE SCALE
what a single step hides: ×10 in recorded amplitude and roughly ×32 in released energy — drawn to true scale
BASIC PHYSICS FORMULAS
fifteen formulas · every letter explained beneath it
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
SPEED THRESHOLDS
six thresholds where a different physics begins · every figure computed, not typed
ANIMALS
the main branches — from comb jellies to chordates · who is actually related to whom
VERTEBRATES
from lamprey to bird · and why "fish" and "reptiles" are not groups