People use many different products made from plastics every day. But conventional plastics such as polyvinyl chloride (PVC) do not always have a good reputation in society at large. Bioplastics such as thermoplastic starch (TPS) promise to be better alternatives but are they really better than conventional plastics? This article presents a new form of pedagogy that examines learning about technical products within society. The product-testing method introduces students to the fact that consumer magazines and organisations are not truly objective. Instead, they represent a collection of individual opinions that influence the final, published materials available to the public. The final evaluations depend on negotiation, compromise and weighting factors. The product-testing method offers students an opportunity to recognise that such apparently objective processes need to be evaluated carefully and critically. This is demonstrated using an example taken from the chemistry of plastics and their evaluation with respect to sustainability.