22.1- Introduction
• use current units of mass, length, area, volume and capacity in
practical situations and express quantities in terms of larger or
smaller units
Convert between units including units of area and volume.
e.g. between mm2 and cm2 or between cm3 , m3 and litres

22.2-Compound units
Change freely between related standard units (e.g. time, length, area, volume/capacity, mass) and compound units (e.g. speed, rates of pay,
prices, density, pressure) in numerical and algebraic contexts
A Compound measurement is a measurement that uses more than one quantity.
Density
Density is calculated by mass ÷ volume. So density is therefore written as mass per volume.
The most common units used to measure density are\(\frac{kg}{m^3}\) kilograms divided by metres cubed, or \(\frac{g}{cm^{-3}}\) or g cm^-3grams divided by centimetres cu