Measurement
Map
Arrows point from what you learn first to what it opens.
- Proven to depth123
- Open
- Locked
- Comes back deeper
Learning path
In the order the concepts build on each other.
- MeasurementReadyMeasuring means comparing a thing with something everyone knows, so the answer means the same to everyone - unlike words such as long or heavy.
- UnitsLockedA unit is an amount everyone agrees to measure with, checked against a standard. Every measurement is a number and a unit, and a bigger unit gives a smaller number.Opens after: Measurement
- LengthLockedHow long, tall or far something is. Measured in metres, centimetres, millimetres and kilometres in most of the world, and in inches, feet and miles in a few places.Opens after: Units
- TemperatureLockedHow hot or cold something is, measured with a thermometer in degrees. On the Celsius scale water freezes at 0 and boils at 100; on the Fahrenheit scale at 32 and 212.Opens after: Units
- TimeLockedHow long something lasts, measured in seconds, minutes, hours and days. The day comes from the Earth's spin; the sixties come from ancient Babylon.Opens after: Units
- Metric prefixesLockedKilo means a thousand, centi a hundredth and milli a thousandth. The same few prefixes work with every metric unit, which makes the system easy.Opens after: Length
- MassLockedHow much stuff is in a thing, measured in grams and kilograms. Weight is how hard a planet pulls on that stuff: on the Moon your weight changes, but your mass doesn't.Opens after: Metric prefixes
- Unit conversionLockedWriting the same measurement in a different unit. Within the metric system it is moving the point; between systems, rough rules like a mile is about 1.6 kilometres.Opens after: Metric prefixes
- The SI systemLockedThe International System of Units: the metre, kilogram, second, kelvin and a few more units that nearly every country agreed to share, so measurements mean the same everywhere.Opens after: Length, Mass, Time, Temperature
- VolumeLockedHow much space a thing takes up or a container holds, measured in litres and millilitres. One litre of water has a mass of about one kilogram.Opens after: Mass