Studies about lifespan cognitive development, such as Piaget's stages of cognitive development, are important because they establish cognitive milestones. Teachers can plan developmentally appropriate curriculum that accommodates students' conceptual and logical growth. For example, educators can plan daycare activities or classroom lessons that incorporate the permanence of objects because they know at what age a child should be able to grasp this concept.
Research involving lifespan physical development is necessary so that it is easier to identify if a child is developing physically at the expected rate. A child that is having difficulty with sensory perception, vision, hearing, or motor skills, for example, can be identified early so that medical treatment can be sought for early intervention.
Studies that identify the appropriate social milestones over a person's lifespan are important because they are indicators of what social behavior is acceptable and appropriate and which behaviors are not. Children demonstrating certain behaviors, such as a lack of attachment, withdrawal, rage, lying, difficulty with relationships and cruelty to animals or other children, may indicate serious mental health issues. Early intervention is beneficial.
Theories of stages of development, such as the moral stages created by Lawrence Kohlberg, reveal people's inherent worth and potential. Moral understanding, compassion, resentment and feelings of shame and guilt affect a person's behavior and his mindset and attitudes. Studies about the lifespan stages of moral development provide baselines for healthy development so that any lack of growth can be identified early.