Temperature
Hot and cold can be felt but not seen. How do you put a number on temperature, and what happens below zero or on a different scale?
Where you are 4 inside
What this area is about
A thermometer only shows a liquid or a bar rising and falling. A temperature scale marks it the same way everywhere, so a reading means the same thing to everyone. This area reads that scale, names the scales in use, goes below zero, and trades one scale for another.
How these fit together
The procedure. Reading a thermometer takes a temperature off a marked scale, working out what the unnumbered marks stand for.
The definitions. Temperature scales sets up Celsius (at sea-level air pressure, water freezes at 0^\circ and boils at 100^\circ), Fahrenheit (32^\circ and 212^\circ) and Kelvin, which starts at absolute zero.
Below zero. Temperatures below zero and temperature change names readings under zero with negative numbers, compares them, and finds how far the temperature moved.
Changing scales. Converting between Celsius and Fahrenheit uses a rule that both stretches, by 180 Fahrenheit steps for every 100 Celsius steps, and shifts, by 32.
A path through it
Reading a thermometer first. Then the scales, and, separately, temperatures below zero, which also needs adding and subtracting integers. Converting comes last: it needs the scales and substituting into a formula.
Finish here and you can read, compare and convert any everyday temperature.