Units from the metric system can be used to describe the mass, volume or length of an object. Mass is measured in grams (g) and kilograms (kg). Volume is measured in millilitres (ml) and litres (l).

Before measuring something, it is important to know which unit to use. Estimating its approximate size by comparing it with a more familiar object can help. In order to find a suitable unit of measure ...

When the rest of the industrial, modern world converted to metric measurements decades ago, Americans decided to stick to their traditional units of measure. Although American scientists did mostly ...