Materials
Metals come from rocks called ores.
They are strong, hard and shiny materials
that can be hammered into different shapes without breaking.
Many metals are good conductors of
heat and electricity.
Some metals are magnetic. Iron is
the most magnetic metal. Steel is also magnetic because it is made of mostly
iron.
Their properties make them useful for
objects such as cutlery, saucepans, cars and coins.
Plastics are materials made from chemicals and
are not found in nature. They are strong and waterproof, and can be made into
any shape by applying heat. Plastics can also be dyed different colours or made
to be transparent.
Plastic is not magnetic. It is a good
electrical insulator as it does not conduct heat or electricity.
Plastics
are used to make all sorts of things, such as bags, bottles and toys.
Glass
is made by melting
sand and other minerals together at very high temperatures.
Glass is normally transparent and
can be made into many different shapes. Thick glass can be strong, but thin
glass will break very easily.
Glass is used for objects that need to
be transparent such as windows and spectacles.
Wood
comes from trees. It is strong, flexible and long
lasting.
Wood is used to make things such as
furniture that need to be strong and last a long time.
Wood is an insulator of heat and
electricity.
Fabric
s are made from thin fibres woven
together.
·
Some fabrics, such as wool, cotton and silk, are natural (the
fibres come from living things).
·
Some fabrics, such as polyester and nylons are made
from synthetic fibres, which are made in factories, from
chemicals.
Different fabrics have different
properties. Fabrics can be stretchy (a pair of tights),insulating (keep
you warm, like a woollen coat) or absorbent (a towel).
Fabrics are used to make clothes as they
are flexible and comfortable, can be warm and do not wear out easily.
Material
properties
Materials have different properties that
make them useful for different jobs. Here are some properties that materials
have.
Transparent or opaque
Transparent materials do let light
through (you can see through them). Opaque materials do not let any light
through (you cannot see through them).
Waterproof
Waterproof materials do not let water
through and do not soak up water.
Absorbant
Absorbent materials soak up water and
let water pass through them.
Strong or weak
Strong materials are very difficult to
break. Weak materials break easily.
Flexible
Flexible materials are easy to bend.
Rigid
Rigid materials are difficult to bend.
Hard
Hard materials are difficult to scratch.
Magnetic
Magnetic materials are attracted to
magnets.
Conductors
Some materials are good conductors of heat.
This means heat can travel through them easily.
Some materials are good conductors of electricity. This means electricity can travel
through them easily.
Insulators
Some materials are insulators of heat.
This means they do not allow heat to travel through them very easily. Some
materials are insulators of electricity. This means that electricity cannot
travel through them.