Temperature Explorer

Pre-Algebra · Axiom Academy

Negative numbers, made obvious by a thermometer: zero is the dividing line, below it is negative, and warmer always means greater. Below zero, the numbers go negative You already read temperatures every day — so you already read negative numbers, even if no one called them that. A thermometer is a number line stood on end, with 0°C as the line that splits warm from cold. Watch the mercury fall straight through zero. The reading starts warm at +15°C and the mercury drops. As it sinks past the 0° mark it keeps going — into −1, −2, −3… — and settles at −15°C . Notice where it stops: exactly as far below zero as it started above . That mirror is what the minus sign means. Above zero is positive, below zero is negative — and −15 is the mirror image of +15 across the zero line. Warming adds, cooling subtracts — and you can cross zero It is −5°C outside. Drag the slider to make it warm up (mercury rises, you add degrees) or cool down (mercury falls, you subtract ). Watch the marker walk along the number line — when the change is big enough to cross the 0° mark, the answer flips from negative to positive. Adding moves you up (warmer), subtracting moves you down (colder); zero is just the place where the sign changes. Higher on the thermometer is the greater number

This is the written version of the interactive lesson above. See the full Pre-Algebra course.