The document discusses why different materials are used to make different objects and lists some important material properties. It asks which materials would be suitable for making a chair, book, and wire jacket based on factors like strength, price, appearance, and environmental impact. Some key material properties listed include color, weight, hardness, flexibility, conductivity, transparency, and resistance to heat, corrosion, and humidity.

1. Why do we use different materials to make different things ? Javier Gómez Calzada 1ºESO, 3ºESO

2. Why do we use different materials to 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

3. Most important types of materials Metals (eg steel, copper) Wood (eg oak, MDF) Plastic (eg vinyl, PVC) Fabric (eg cotton, polyester) Ceramic (eg clay, porcelain)

4. Some 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

5. Which materials would you use for these objects? Why? Chair Pan Book Wire Jacket Use the words Write a sentence using each of 22 properties in the previous slide. Be sure you know its translation to Spanish.

6. A CHAIR could be made of wood 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 more confortable It is cheaper than wood It is not as heavy as wood