Choosing between a polystyrene or a paper cup is more complicated than you may think! This Dragons Den style resource is a great way to develop students' understanding of the ecological and social footprint of materials.
Paper cups have an environmental impact. Although the cups themselves are made from renewable resources (wood chips), paper cups actually consume more non-renewable resources in their manufacture than cups made of polystyrene foam, since converting the wood chips to paper pulp requires energy. During their life cycle, the only significant effluent of polystyrene cups is pentane. In contrast, the manufacture of paper requires several inorganic chemicals and creates large amounts of water effluents. Similarly, recycling polystyrene cups has less impact than recycling paper cups. Paper cups are, however, more biodegradable than polystyrene cups, with the caveat that in an anaerobic landfill paper cups will generally remain undegraded for a long time.