This paper presents a study on discovery learning of scientific concepts with the support of computer simulation. In particular, the paper will focus on the effect of the levels of guidance on students with a low degree of experience in informatics and educational technology. The first stage of this study was to identify the common misconceptions about density, starting from a literature review. Forty eight students (25 M and 23 F) from two high schools in Vanuatu were then involved in the study. These students were divided into three groups according to the different levels of guidance they received (Unguided; Minimum guidance, Maximum guidance). A pre and post activity questionnaire was designed containing 12 questions. The students underwent a training session with computer simulation about density. Using a descriptive and an inferential statistics method, scores obtained from the three different groups were compared during pre-test and post-test analyses. From the analyses it was found that the construction of knowledge from discovery learning activities occurs with or without guidance, however the amount of guidance received has an influence on the depth of conceptual understanding.