Determining pre-service science teachers' alternative conceptions concerning the subjects of osmosis and diffusion

The purpose of this study is to determine pre-service science teachers' alternative conceptions regarding the subjects of diffusion and osmosis and to identify their status of understanding the structure of cell membrane and the transport of substances across cell membrane at the molecular level. Also, the study aims to investigate whether or not there is a relationship between learning the structure of cell membrane and the transport of substances across cell membrane and visual literacy. The study employed the survey method. The study group consists of 141 pre-service science teachers studying at Kastamonu University Faculty of Education in the 2015-2016 academic year. The study was conducted with students from all grades. The study used an open-ended drawing test prepared for identifying the students' status of understanding the structure of cell membrane and the transport of substances across cell membrane at the molecular level. The study also employed the two-stage conception test developed by Odom and Barrow to determine misconceptions concerning the subjects of diffusion and osmosis. The first stage of this test measured the students' knowledge about the subject, while the second stage questioned the reasons for the answers given to the first stage. To determine visual literacy competencies of the participants, the study employed the Visual Literacy Scale prepared by Kiper, Arslan, Kıyıcı & Akgün (2012), who also conducted its validity and reliability study. The scale evaluated student competencies according to six factors. The findings were described through percentage, frequency, mean, and standard deviation values. The correlations of tests both within themselves and with other tests were checked. One-way analysis of variance (ANOVA) was made to test the significance of the difference between the mean scores obtained by the students from the open-ended questions and the diffusion and osmosis conception test by grade. The study found out that the students did not have an adequate understanding of the structure of cell membrane and the transport of substances across cell membrane at the molecular level. In the two-stage conception test, the students' average was 6.39 out of 12 in the first stage measuring their knowledge about the subject and 2.97 when two stages were evaluated together (i.e. both knowledge about the subject and the reason for the answer). This shows that the students failed to provide an explanation for the answers they gave in the first stage. The pre-service teachers were seen to have alternative conceptions on every subject area, but mostly on the subjects of diffusion and osmosis process, the granular structure and random motion of matter, the effect of vital forces on diffusion and osmosis, and the kinetic energy of matter. According to the analysis results for the Visual Literacy Test, the students had the highest mean score in the first factor, which measured their capability to feature visual quality by using Office software, and had the lowest mean score in the sixth factor, which measured their capability to make sense of the messages contained in the visuals. No correlations were detected between the Visual Literacy Test and the other tests. However, a weak positive correlation was detected between the scores of the students giving correct answers to both stages of the diffusion and osmosis test and the scores obtained in the sixth factor, which measured their capability to make sense of the messages contained in the visuals. One-way analysis of variance indicated that rise in grade had a positive effect on achievement. The test items involving a difference were found to be the open-ended items which were aimed at determining the degree to which cell membrane was understood at the molecular level and questioned the diffusion of water through cell membrane, the diffusion of polar substances or ions through cell membrane, the diffusion of nonpolar or oil soluble substances through cell membrane, and the transport of molecules that are big enough to pass through cell membrane through it via active transport.