How schemas adapt and how reasoning progresses from sensory action to symbolic, concrete and abstract thought.
Five Core Concepts
Concept 01
The Mechanisms of Adaptation (Schemas)
Core principle/rule: Piaget described children as active “little scientists” who build cognitive frameworks called Schemas. Cognitive growth occurs through adaptation to new environmental information.
AssimilationFit new information into an existing schema without changing it—for example, a child who knows “dog” sees a cow and calls it a “big dog.”
AccommodationAlter an existing schema or create a new one when new information contradicts the old—for example, learning that cows give milk and moo, then forming a “cow” schema.
EquilibrationThe driving force behind cognitive growth: the mental balancing act between assimilation—equilibrium—and accommodation—disequilibrium.
Concept 02 · Birth to 2 Years
Sensorimotor Stage
Core principle/rule: Infants construct an understanding of the world by coordinating sensory experiences—seeing and hearing—with physical motor actions.
Key facts
Learning is primarily through trial and error and reflex actions.
Crucial milestone:Object Permanence, usually beginning around 8–9 months—the understanding that objects continue to exist even when they cannot be seen, heard or touched.
Concept 03 · 2 to 7 Years
Preoperational Stage
Core principle/rule: Children begin to represent the world with words, images and drawings, but remain “pre-operational”—they lack mental operations and logical reasoning.
Key facts
Egocentrism: Absolute inability to distinguish one's own perspective from another's; children believe everyone sees the world exactly as they do.
Animism: Belief that inanimate objects—such as toys, sun or clouds—have lifelike qualities and can act.
Centration: Focus exclusively on one salient aspect of a situation while ignoring other relevant features.
Failure of conservation: Because of centration, children do not understand that changing appearance does not change quantitative properties—for example, the same water in a taller, thinner glass.
Concept 04 · 7 to 11 Years
Concrete Operational Stage
Core principle/rule: Children can perform logical operations, but their logic is tied to concrete, physical objects and real-world events; they cannot yet grasp hypothetical scenarios.
Key facts
Mastery of conservation: Quantity, length or number are unrelated to an object's arrangement or appearance.
Reversibility: Mental operations can be reversed and returned to their original state—for example, if 3 + 4 = 7, then 7 − 4 = 3.
Seriation: Sort objects or situations by characteristics such as size, colour, shape or type—for example, arranging sticks shortest to longest.
Concept 05 · 12 Years and Adulthood
Formal Operational Stage
Core principle/rule: Adolescents move beyond concrete experience and begin thinking in abstract, highly logical and idealistic terms.
Key facts
Hypothetico–Deductive Reasoning: Develop hypotheses—best guesses—about solving problems and systematically deduce the best path rather than relying on trial and error.
Abstract thought: Mentally manipulate concepts without physical reality, such as justice, infinity and philosophical ethics.
Quick Reference
Piaget's Stages & Milestones Matrix
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Developmental Stage
Age Bracket
Core Cognitive Limitation
Major Cognitive Achievement
1 · Sensorimotor
Birth to 2 years
Lacks symbolic thought.
Object Permanence—knowing hidden things still exist.
2 · Preoperational
2 to 7 years
Egocentrism & Centration—cannot use logic.
Symbolic thought—language and pretend play.
3 · Concrete Operational
7 to 11 years
Cannot grasp abstract or hypothetical logic.
Conservation & Reversibility—logical thought applied to physical objects.