The term "ecological rucksack" was coined by Friedrich Schmidt-Bleek. This image illustrates the material intensity and therefore the ecological impact of an artefact. The rucksack of an artefact is expressed in kilograms and results from the totality of all material inputs from resource extraction to use and disposal. This includes all production steps (incl. energy, material, transport) and resources used (biotic, abiotic, water, soil, air). Only water and land consumption are not included in the rucksack. However, it is not only the consumption of natural resources that is relevant when it comes to sustainable consumption, but also the intensity and duration of use of consumer goods. The MIPS factor puts the ecological rucksack in relation to the intensity of use. MIPS is the abbreviation for Material Input Per Service (unit). The more intensively a product is used, the lower the MIPS factor. Disposable items that are disposed of after a single use have a factor of 1. The first double lesson introduces the concept of the ecological rucksack. The second double lesson will be used to discuss the relevance of useful life in relation to material intensity. In the third and fourth double lesson, the pupils expand their knowledge of ecological rucksacks by developing a quiz and asking people about their knowledge of the true costs of our consumption.