The document discusses two approaches to human development - the traditional approach and lifespan approach. The lifespan approach views development as occurring throughout the entire lifespan from childhood through adulthood, rather than leveling off in adulthood. It identifies five key characteristics of lifespan development: it is lifelong, plastic, multidimensional, contextual, and involves growth, maintenance, and regulation. The stages of development span from prenatal to late adulthood. Research methods examined include case studies, longitudinal studies, and observational studies. Ethical principles for research with children emphasize non-harm, informed consent, and respect for privacy.