Schemas
"A schema describes both the mental and physical actions involved in understanding and knowing.  Schemas are categories of knowledge that help us to interpret and understand the world.  In Piaget's view, a schema includes both a category of knowledge and the process of obtaining knowledge.  As experiences happen, this new information is used to modify, add to, or change previously existing schemas." (Van Wagner, 2009)
For instance, if a child has only seen a palm tree then the child's schema is that every tree has palms and coconuts.  When the child sees an olive tree they process the information and change their schema.