P3 Materials (Concept Map)

Properties decide the use

The five properties we compare, and how each one matches a material to its job

The five properties: strength, flexibility, absorbency, floating or sinking, and how much light passes through.

Strong withstands a heavy load without breaking; flexible bends without breaking.

Waterproof means it does not absorb water; light may pass through a material fully, partly or not at all.

A material is chosen by matching its properties to the job — the strongest bag, the waterproof raincoat.

Compare one property at a time, under the same conditions, so the comparison is fair.

The five properties

Strengthhow well a material withstands a load without breaking or tearing

Flexibilityhow well a material bends without breaking; the more flexible it is, the more it bends

Absorbencywhether a material soaks up water — one that does not is waterproof

Two more ways to compare

Floats or sinkswhether a material stays on or near the surface of water, or sinks

Lets light througha material may let most light through, some light through, or no light at all

A fair comparisoncompare one property at a time, under the same conditions

Strength and flexibility in use

Strong materialsused where an object must carry heavy loads without breaking

Flexible materialsused where an object must bend, wrap or stretch without breaking

Weak or rigidweak materials break or tear easily, and rigid ones do not bend easily

Water and light in use

Waterproofused for objects that hold liquids or keep the user dry

Absorbentused for objects that soak up water, such as a towel

Letting light throughused where we need to see through an object, such as window glass

Common materials

Wood and metalwood comes from trees, floats and is not flexible; metal comes from the ground and sinks

Rubber and plasticrubber comes from tree sap; both are flexible and waterproof; plastic generally floats

Glass and ceramicglass is made by heating sand and lets light through; ceramic from clay breaks easily

Choosing a material

Match the jobchoose a material whose properties suit what the object must do

A bagthe material that held the most weight without breaking was chosen — it was the strongest

A raincoatthe material that absorbed no water was chosen, because a raincoat must keep the user dry