States of matter (age 7 to 9)

A big idea in chemistry is the idea of how substances behave and change. This is important because we are surrounded by objects made from different materials, each with their own physical properties that make them suitable or unsuitable for different purposes. How substances behave helps us to categorise them into three common states (solid, liquid or gas) and this, in turn, can help us to understand and classify the materials around us. Similarly, an understanding of how substances change helps us to recognise that some materials change state if heated or cooled and that one substance can exist in three different states.

These diagnostic questions and response activities support pupils in being able to:

• Identify substances that are in the liquid state.
• Know that some materials can change from the solid state to the liquid state when heated.
• Recognise that when water boils it changes into the gas state.
• Recognise that air takes up space and has mass and is therefore matter.
• Explain the observed decrease in volume of water during evaporation in terms of a change into the gas state.

The resources include details of common misconceptions and a summary of the research upon which the resources are based.