# Measuring density

Density is a derived quantity - we measure two other quantities (mass and volume) and then calculate density. A first time learner, however, deserves first to understand the concept - and that takes careful teaching and a little time. Moreover, different techniques are required for solids, liquids and gases.

Many students imagine that a gas such as air has no mass. Carefully 'weighing' air can help students later to answer some startling questions: What's the mass of air in a classroom? The height of the atmosphere? The average speed of air molecules?

**Experiments**

Measuring and weighing solid blocks [1]

Measuring the density of regular solid shapes [2]

Weighing liquids [3]

Understanding measuring cylinders [4]

Measuring the density of liquids [5]

Measuring the average density of a student [6]

Weighing a sample of air – a rough estimate [7]

Weighing air [9]

**Related Guidance**

Introducing the concept of density [10]

Rough and ready measurements [11]