This paper reports data, part of a cross-sectional study about the use of pupil's drawings as a means of probing the development of 195 Brazilian pre-school children (4 to 6 year-olds) and 681 primary school pupils 1st Grade through 4th Grade (7 to 10 years of age) conceptions of the human brain. The aims of the present study is to analyze how the conception of the brain develops, how they represent their brains, and whether it is based on historical models or current scientific knowledge, in their interaction with school and society at large. The methodology involved the presentation of a contour of the head and neck drawn on the blackboard in the classroom, and children were asked to draw what they think they have inside their heads. After the drawings were collected some pupils were interviewed to explain their drawings. Classification of the collected drawings were interpreted on the perspective of historical models of the brain and scored following a 6 level rating scale depicting degrees of neuroanatomical resemblance. Gender and age were taken into consideration. The results show that younger pupils are adepts of mental ideas in their representations of the brain, i.e. what the brain does, but progressively as they get older, start to develop a more morphological representation of the brain. Knowledge obstacles for learning about the nervous system and elementary neuroscience implications are discussed. (Contains 4 tables and 6 figures.)