Children spend some time in a given stage with an unchanging set of skills and suddenly move into a new stage exhibiting a whole new set of skills more or less at once. Stages followed in same order, no skipping or backtracking. Motor activity and physical interaction is crucial for knowledge acquisition. Early language development starts here (start to hear and process language don"t speak it though) Object permanence develops at around 8 months of age a child understanding that an object still exists when it can no longer be observed directly. Do not understand abstract or formal operations yet. Interpreting new info in terms of previously understood theories and knowledge. Changing one"s current theory, understanding or knowledge in order to cope with new information. Learning process for the child to develop new categories. Balancing assimilation and accommodation to maintain a stable understanding of the world while still allowing for development.