Students do not come to school as blank slates to be filled with instruction. Rather, they come to school with considerable knowledge, some correct and some not. Either way, that knowledge is based on intuition, every-day experience, as well as what they have been taught in other settings.
Teachers and researchers generally refer to preinstructional knowledge as preconceptions. Since a considerable amount of our knowledge is organized by subject matter (mathematics, science, etc.), so too are our preconceptions. Before beginning instruction on any new topic, teachers need to know their studentsâ€™ preconceptions because learning, and therefore instruction itself, varies depending on whether studentsâ€™ preconceptions agree with the concepts being taught or contradict those concepts.