Healthy children's understanding of their blood: implications for explaining leukaemia to children

Explanations of leukaemia to children usually include details of blood function and structure. In study 1, 3-year-olds (N = 25), 4-year-olds (N = 25), and 8-year-olds (N = 27) were interviewed about their understanding of the properties of blood and any occasions when they remembered seeing blood. They were also asked whether other animals and objects had blood or not, and to give reasons for this. Children justified their decisions in three ways: only people have blood, they had seen blood on a particular occasion, or only creatures which shared a human property (walking or talking) could have blood. In study 2, an intervention to increase children's understanding of the function of different blood cells is reported. It was partially successful. Children who reported an incident in which they saw blood were more likely to recall information about the function of red cells, white cells and platelets compared with children who did not report a previous experience (p < .001). In terms of explaining leukaemia to a child, we conclude that explanations should build on previous experience, and not be based simply on chronological age.