Download c2_03_lesson

OCR 21st Century Science: C2 Material choices
c2_03 Natural and synthetic materials
Resources
Student Book pages 144−145  Homework pack c2_03
Files on Teacher Pack CD: c2_03_worksheet
Learning outcomes
C2.2.1 recall that the materials we use are chemicals or mixtures of chemicals, and include metals, ceramics and
polymers
C2.2.2 recall that materials can be obtained or made from living things, and give examples such as cotton, paper,
silk and wool
C2.2.3 recall that there are synthetic materials that are alternatives to materials from living things
C2.2.4 recall that raw materials from the Earth’s crust can be used to make synthetic materials
ICT focus: Research on various materials and producing a presentation/display.
In this lesson students are learning to:
 explain that many of the materials we use come from living organisms
 explain that other materials are found in the Earth
 explain that new materials can be made from chemicals
Key vocabulary
chemicals 
metals  malleable  ceramics  polymers  mixture
natural materials  synthetic materials
Obstacles to learning
The brief diversion to metals and ceramics could be confusing because the main interest in this module is
polymers. Some students may have difficulty in understanding which materials are synthetic.
Stimuli and starter suggestions
 Ask the students to look around and make a list of all the materials that they can see. Taking the materials
examined in the previous two lessons, they should see rubbers – shoes, feet of stools; plastics – pens, rulers,
power sockets; fibres – clothes. They should also see metals – stools, benches, pipes, Bunsen burners, wires;
ceramics – window glass, glassware, cement or brick in the walls, teacher’s coffee mug; and perhaps polymers
(all the rubber, plastic and fibres). Ask what is common to all the materials – they are all chemicals made up of
atoms of the 90 or so elements found on Earth.
Learning activities
worksheet c2_03
Low demand  Discuss the properties of metals and ceramics and explain what is meant by a polymer. Explain
that all these materials are substances/chemicals – some pure (single substance, e.g. copper wires) others
mixtures (most materials). Students should make lists of materials classifying them as metals, ceramics or
polymers. The worksheet provides some exercises matching the material with its properties and uses.
Teaching and learning notes: At this stage students do not need to know about how polymers are formed, so
they can be referred to simply as molecules made up of a very large number of atoms.
Standard demand  Use the examples in the room to explain the meaning of the terms ‘natural’ and ‘synthetic’ as
applied to materials – see Student Book p.143-4. Natural materials are derived from plants and animals and they
are not changed chemically before being useful – e.g. cotton and paper are plant cellulose; silk and wool are
animal proteins. Synthetic materials, on the other hand, have undergone a chemical reaction in which simpler
materials, often obtained from the Earth’s crust, are joined together – e.g. polymers from substances in crude oil.
Note there are some difficult -to-categorise materials such as rayon – plant cellulose that has been processed into
fibre. Students should make lists of plant/animal materials and synthetic materials noting their sources. The
worksheet provides other tasks exploring these ideas.
Teaching and learning notes: Metals are not covered by the classification given here in that they are not from
organisms and not produced by a synthesis reaction. Ceramics can be seen as being synthetic because they are
formed by a combination of substances and undergo a chemical change.
COLLINS NEW GCSE SCIENCE
© HarperCollinsPublishers Ltd 2011
c2_03 Lesson continued
High demand  Explain that many synthetic materials have properties similar to natural materials – e.g. natural
and synthetic rubbers. Ask students to suggest why a synthetic material may have replaced the natural form.
Answers should include cost, availability of the raw material and better properties. After discussion, students should
record the answers to the question. They can carry out research and write up a brief report on the development of
such substitutes such as neoprene rubber, nylon, Bakelite. The worksheet gives further tasks on this topic.
Plenary suggestions
Go back to the list of materials in the starter and ask the students to state if they are natural or synthetic (with the
exception of the metals) and their sources.
Student Book answers
Q1 For example: a) jewellery, cars, bicycle, school furniture, cans, cutlery
b) mugs, crockery, bricks, windows, houses
c) clothes, tyres, plastic bottles, rubbers, curtains
Q2 Metals – body, engine
Polymers – seat covers, dashboard, interior, tyres
Ceramics – windows, brake blocks (a bonus point!)
Q3 For example: cotton, paper, flax, hemp
Q4 Polythene is made from small molecules found in crude oil; wool comes from sheep.
Q5 Synthetic materials can be made in larger quantities more cheaply than natural materials and perform better.
Q6 Synthetic materials can be designed to have the properties needed for a particular purpose.
Worksheet answers
Activity 1 (Low demand)
Q1 Metal
Ceramic
Metal
Polymer
strong when stretched
strong when squashed
conducts electricity
very large molecules
bridges and machines
building materials
wires for carrying electricity
makes rubbers, plastics and fibres
Q2 Elements: copper, aluminium, lead
Mixtures: steel, brass, bronze
Activity 2 (Standard demand)
Q1 Natural: cotton (plant), paper (plant), leather (animal), wool (animal), silk (animal)
Synthetic: polythene (oil), glass (minerals), nylon (oil) , concrete (minerals)
Q2 Cotton, paper, leather, wool, silk, polythene, nylon
Activity 3 (High demand)
Q1 Wood/Bakelite; rubber/neoprene; silk/nylon; leather/PVC; cotton/polyester
COLLINS NEW GCSE SCIENCE
© HarperCollinsPublishers Ltd 2011