Knaph
Explore

Measurement

Study it inMeasurement Level 1: Units and the SI System

Map

Arrows point from what you learn first to what it opens. Point at a concept to light up its chain and where it comes back deeper. Right-click a concept (or press and hold it) for its lessons and stories.

  • Proven to depth123
  • Open
  • Locked
  • Comes back deeper
Depth 2Depth 2Depth 2LengthMassMeasurementMeasurement precisionMetric prefixesTemperatureThe SI systemTimeUnit conversionUnitsVolumeDecimalsIn FractionsMeanIn Statistics

Learning path

In the order the concepts build on each other.

  1. MassReadyHow 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.
  2. MeasurementReadyMeasuring means comparing a thing with something everyone knows, so the answer means the same to everyone - unlike words such as long or heavy.
  3. TemperatureReadyHow 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.
  4. 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
  5. 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
  6. 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
  7. 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
  8. Measurement precisionLockedEvery measuring tool reads only down to its smallest marking: a ruler marked in centimetres has a precision of 1 cm, one marked in millimetres 1 mm, a kitchen scale showing tenths of a gram 0.1 g. A result is written to the tool's precision, never finer, rounding to the nearer mark when an edge falls between two, and the precision is reported with it. How careful the measurer is matters too: start at zero, look straight on.Opens after: Length, Mean
  9. 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
  10. 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
  11. 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: Decimals, Metric prefixes

Connections to other domains