Ima

Materials can change in different ways. Some changes can be reversed, and some cannot.

Physical changes

A physical change changes the shape, size, or state of a material, but no new material is made.

Examples:

• ice melting,

• paper folding,

• cutting wood.

Chemical changes

A chemical change forms a new material.

Examples:

• iron rusting,

• wood burning,

• cooking food.

Changes caused by heat

Heating can:

• melt materials,

• soften them,

• or burn them.

Changes caused by water and air

Water and air can slowly change materials.

Examples:

• wood rotting,

• metal rusting,

• rocks weathering.

So, materials can change because of:

• heat,

• force,

• water,

• air,

• or chemical reactions.