1. Raising awareness of resources
So far in this module we have explored the origins of different materials, considered how they may be classified by their properties and how they may be processed and used in different ways depending on their states.
In this section, we try to make our pupils aware that we have limited supplies of many materials on the Earth. In Case Study 1, we read how a teacher introduces this idea by brainstorming a list of materials in terms of ‘renewable’ and ‘non-renewable’. (See Key Resource: Using mind maps and brainstorming to explore ideas.)
One very important resource that is in limited supply is crude oil. Do you know how many materials are made from crude oil? Crude oil is a mixture of liquids. It isn’t any use until the mixture has been separated at an oil refinery. The crude oil is boiled and each part of the mixture boils at a different temperature. This separation is called distilling and the different parts of the mixture are called fractions. Each fraction is then used to make different products.
In Activity 1, you use a diagram to help pupils appreciate how dependent we are on crude oil. You could follow this up with a display of products based on crude oil in your classroom – pupils could draw pictures or use images from catalogues or magazines.
Case Study 1: Getting the big picture
Amani in Khartoum, Sudan, draws a line down the middle of the chalkboard and writes the headings ‘Renewable’ on the left and ‘Non-renewable’ on the right. Then she helps her pupils through a brainstorm where they suggest names of materials and matter that are part of their everyday lives. They decide what family of substances each belongs to and where it fits on the board. (See Resource 1: Renewable and non-renewable resources for a typical result of such a whole class activity). They copy the final diagram and add to it over the next few weeks as they study renewable and non-renewable materials.
Activity 1: Unmixing mixtures – crude oil
Many sources provide a diagram explaining how crude oil is processed in a petrol refinery. (Resource 2: Products from crude oil gives an example.)
Remind your pupils about how water evaporates and leaves behind the impurities – Activity 2 in Section 3 – and then help them realise that other substances also evaporate to give gases. When they cool, these gases condense back to a liquid. Think of any cooking area; the walls and ceilings have to be cleaned of greasy deposits, formed when the vapours of hot fat and oils condense.
Explain that crude oil is a mixture of liquids called fractions; each fraction evaporates at a different temperature.
Analyse the diagram with your pupils – how many different ‘fractions’ are produced? How are the fractions different? What is made from each fraction?
Then divide your class into groups and ask each group to research a different group of products – they can find out uses, biodegradability (whether or not something rots away), safety. (See Resource 2 for suggestions for this type of work.)