The use of visual representation to learn science can be traced to Louis Agassiz, Harvard Professor of Zoology, in the mid-19th century. In Agassiz's approach, students were to study nature through carefully observing, drawing and then thinking about what the observations might add up to. However, implementation of Agassiz's student-centered approach has struggled with the conflict between science as a form of developing "mental discipline" in which mastery of scientific facts is the goal and science learning as a socially situated activity with an emphasis on the process of learning, not merely its products. Present-day attempts to have students draw to learn science often succumb to these same conflicts, limiting their full realization.