Here we focus on those scientific concepts that are the hardest to explain to children. We break it down into what pupils need to know and outline the background science. Even though much of the background science does not need to be taught to primary aged children, it is useful for you as a teacher when addressing misconceptions and children’s challenging questions. 

Please refer to your national curriculum documents when planning your sequence of work and ensure that you teach the correct knowledge for your year group. 

What do children need to know about materials? 

Materials is a large topic with many important connections to your pupils’ learning in related topics: forces, states of matter, electricity, light and sound. Pupils should begin their understanding of the properties and uses of different materials through play and then develop further by undertaking hands-on investigations and developing their skills of scientific enquiry. We have included some ideas for how to teach materials in part two of this topic guide. 

Key scientific concepts: Pupils need to... 

1. Identify, describe, compare and group a variety of materials based on their properties

2. Use evidence to explain the suitability of a variety of materials for particular uses

3. Explain how some materials can be changed through processes including dissolving, mixing and separating and how these changes are reversible

4. Explain that some changes to materials are irreversible and result in the formation of new materials

1. Materials and their properties

Pupils need to know:

• How to identify a variety of materials and describe them using their properties

• How to compare materials based on their properties and decide how to group them

• The correct scientific vocabulary for describing a material’s properties

Background science

Every material has its own unique properties. A material has physical properties (i.e., the traits it has before it is used) and working properties (i.e., how it behaves when it is manipulated). For example, for the metal copper, electrical conductivity is a key physical property and malleability is an important working property. The key vocabulary children will need to develop when describing materials can be found in the downloads section of Explorify.

2. Uses of materials

Pupils need to know:

• The properties of a material determine its suitability for a particular use 

• Reasons for why certain materials are used for particular objects and in certain circumstances

• How to conduct a test to determine the best material for a particular purpose

Background science

When designing a product, the properties of the materials being used are crucial for determining which will be the most suitable. For example, when designing clothes for sport you would need to think about materials that are lightweight, durable, quick-drying etc. Sometimes materials must be combined, or new materials are created (sometimes accidentally!) to solve a problem. For example, the stainless steel used to make cutlery was invented (by combining certain metals to make a non-rusting or tarnishing metal) in Sheffield in 1913 by Henry Brearley while trying to solve the problem of erosion on the gun barrels used by the British army in WW1.

3. Reversible changes

Pupils need to know:

• Materials can undergo changes in state (e.g. through melting, dissolving, evaporating) that are reversible

• Some materials dissolve in liquid to form a solution and can be recovered from the solution

• Mixtures of materials can be separated in different ways, including filtering, sieving and evaporating 

• Changes to materials can be used to produce something more useful; e.g., melting metal and pouring the molten metal into a mould to make a tool

• How to carry out investigations to demonstrate reversible changes 

Background science

A reversible change alters the state of the matter (i.e., solid, liquid or gas), but no new materials are created, and you can get back the substances that you started with, although it might not look exactly the same. Key reversible changes are:

• Melting and freezing: water changing between a solid and a liquid because of raising and lowering temperature

• Evaporation and condensation: water changing between a liquid and a gas or vapour because of raising and lowering temperature

• Dissolving: Substances such as salt and sugar are soluble (called solutes) because they dissolve in water (called a solvent) to form a solution. A solute (e.g. salt) dissolves because its particles collide with the particles of the solvent (e.g. water) and are gradually spread out through the solvent, creating a salt solution. The salt is recovered (or separated from the water) by boiling the water until it evaporates, leaving the salt behind. It is important to be aware that the solute might not look exactly the same when it is recovered: e.g., small grains of salt do not look the same after being dissolved and recovered through evaporation

• Separation: materials that are mixed together can be separated in a few ways:

  • Filtering: e.g. a mixture of sand and water is passed through filter paper. The larger sand particles are caught by the paper and the smaller water particles pass through the filter paper

  • Sieving: e.g. a mixture of solid particles of different sizes (e.g. soil and gravel)

  • Evaporation: e.g. separating a mixture of salt and water (a solution) 

4. Irreversible changes

Pupils need to know:

• Some materials undergo changes (e.g. through burning, heating a mixture of substances that undergo chemical changes and rusting) that result in the formation of new materials and these changes are not reversible

Background science

When materials undergo an irreversible change, their chemical properties are altered so that a new substance is created, and the original substance cannot be retrieved. Examples include:

• Heating/Cooking: a mixture of raw ingredients are heated, undergoing chemical changes and forming new substances 

• Burning: if you burn wood it is oxidized, and you create carbon dioxide and ash 

• Rusting: if iron is put in water a chemical reaction called oxidation takes place and it is turned into iron oxide (which is the red, flaky substance we call rust)

Ideas to try with your class  

Now you've got the tricky scientific concepts under your belt, try our ideas to help you explore materials with your class in a way they will understand in part two of this topic guide!   

You can also take a look at the related topic guides for forces, states of matter, electricity, light and sound.

Image credit: Lengths of steel in different shapes by Mujecc via Shutterstock SL