Scientific literacy has many components: concept/content knowledge; science process ability; and reasoning ability. This latter component permits an individual to understand the content. According to Piaget, experience is one of the factors mediating the development of reasoning. Therefore, the primary purpose of this study was to investigate what effects two different teaching strategies would have on the development of logical structures. A secondary purpose was to examine the effects of gender on logical development. Four intact classes took part in this study; two (Control) classes receiving instruction involving working at desks and manipulation of materials based on predetermined behaviors and not children's interests; while the other two (Experimental) classes received instruction encouraging them to work on the floor and to examine whatever phenomenon they were exploring by moving about and/or moving and manipulating the apparatus, and to use them in a variety of ways dependent on their own interests. Data were collected using a battery of six Piagetian-type tasks. The chi-square one-sample procedure was used to determine if there was any direct treatment effect and also to see if gender had any effect on the development of reasoning. It was determined that gender had no effect, while treatment did effect the development of reasoning, experimental subjects outperformed control subjects. It was concluded that teachers must take an active role when their students are using manipulatives; they should act as guides encouraging students to examine materials from many vantage points and to utilize materials in ways which seem appropriate to the students' interests and level of understanding.