Many studies have investigated the classification of living things. Our study deals with a different problem: the attribution of life to one component of a living organism, specifically the bones. The task involves not only specifying what we mean by "alive", but also requires "informed thinking" leading to an understanding of the concept of life itself. This study is part of an education programme at the Civic Zoological Museum of Rome. The questions "Are bones alive when they are inside the living body? What evidence do you have to this effect? What are bones made of? Can bones grow? How do they grow? Do children or newborn animals have the same bones as adults?" were addressed to a sample of 189 students aged 7 to 12 taking part in the programme, and to a sample of over one hundred 17-18 year old students visiting the Museum. Not only did the younger students consider bones as non-living entities, so did a high percentage of lower and higher secondary school students, although many of them mentioned their "having cells" and acknowledged their growth. In this paper, we argue that the acquisition of the concept of life should be a priority in the study of biology but, on the contrary, it is rarely the object of deliberate and informed teaching in our schools. (Contains 3 tables.)