Children develop common conceptions about substances as inert objects as a result of their everyday life experiences. In order to promote conceptual development 168 Greek students (aged 13 ndash 14) were involved in a new sociocultural situation a specially designed introductory chemistry sequence. During the sequence the students observed and expressed their ideas about 11 mdash unknown to them mdash substances and 18 interactions between these substances by answering a written questionnaire on various tasks. These tasks comprised description and differentiation of the initial substances and prediction description and explanation of the interactions between them. Twelve of the 168 students were also interviewed. The analysis of the students answers showed that conceptual development did occur during the sequence the students moved from the ldquo concrete substance rdquo conceptual scheme toward the ldquo unknown substance plus properties rdquo scheme and from the ldquo inert mixture rdquo idea to the ldquo interaction rdquo idea. Moreover the students initial reasoning mdash based on the ldquo recognition rdquo of substances mdash evolved toward a primitive ldquo identification rdquo process. Informed by these data we formulate propositions regarding a chemical substances approach in order to further improve students conceptions during the teaching of chemistry.