Carry out simple comparative LCAs for products such as plastic and paper shopping bags.

In the Life cycle assessment subtopic, this objective is about comparing environmental impacts rather than simply naming which product seems greener. For plastic and paper shopping bags, students should consider raw material extraction, manufacture, transport, reuse and disposal. A good comparison uses Life cycle assessment evidence such as energy use, water use, waste produced and number of reuses before making a balanced judgement. The important exam skill is to explain that an LCA conclusion can change depending on which impact is weighted most strongly.