We change over time in almost every way, from our physiology through to our cognitive capacities and personality. This unit explores theories and research around these lifespan changes covering topics including physical, cognitive, and socioemotional development. The unit considers issues at birth, through childhood and adolescences, young and middle adulthood, before finally turning to old age, older age, and finally, death and dying. The unit explores research methodologies unique to developmental sciences such as twin sibling studies and methodologies for assessing genetic influences on psychology. The unit applies our understanding of development to education systems, behaviour management, and healthy aging.