Why do we useWhy do we usedifferent materialsdifferent materials

to maketo makedifferent thingsdifferent things??

Javier Gómez Calzada1ºESO, 3ºESO

Why do we use different materials to Why do we use different materials to make different things?make different things?

Different materials have different characteristics:

• Properties (weight, hardness, elasticity, …) • Price• Appearance• Availability• Easiness/difficulty of use• Effects on health• Effects on environment

Most important types of materialsMost important types of materials

Metals (eg steel, copper)

Wood (eg oak, MDF)

Plastic (eg vinyl, PVC)

Fabric (eg cotton, polyester)

Ceramic (eg clay, porcelain)

Some important propertiesSome important properties

• Colour, shininess• Weight, density• Strength, toughness, hardness, brittleness• Feel, texture• Resistance to heat, resistance to corrosion• Conductivity/insulation (electrical or heat)• Flexibility• Ability to see through: opaque, translucent, transparent• Elasticity, plasticity• Malleability• Ductility

Which materials would you use for Which materials would you use for these objects? Why?these objects? Why?

• Chair• Pan• Book• Wire• Jacket

Use the wordsUse the wordsWrite a sentence using each of 22 properties in the

previous slide.

Be sure you know its translation to Spanish.

A CHAIR could be made of woodwood because• The wood has a good appearance• It is strong, tough• It can be environmentally friendly (it depends on the type of

wood)

• It is not usually expensive (it depends on the type of wood)

But if we want an outdoor CHAIR, maybe it is better to make it of plastic:

• The plastic has a better resistance to humidity,so it will last longer

• It has some flexibility, so the chair can be moreconfortable

• It is cheaper than wood• It is not as heavy as wood