The effect of predict-observe-explain strategy on learner's misconceptions about dissolved salts

Abstract

Misconceptions learners bring to class are in sharp contrast to acceptable science. These misconceptions emanate from a variety of sources including the way educators teach, textbooks used by teachers and from life experiences. These misconceptions at high school (Grade 10) are a potential source of learning difficulty regarding understanding how salts dissolve in water. To assist learners to overcome such difficulties, learner-centred and activity-based intervention, Predict-Observe-explain (POE), was used in this study. The sample consisted of 93 Grade 10 Physical Sciences learners from two neighbouring schools situated in Moutse West circuit, Sekhukhune District, Limpopo Province. 53% of the students involved in this study were males and 47% were females. The purpose of this study was to investigate Grade 10 Science learners’ conceptual understanding of dissolved salts and to explore the use of POE strategy in order to reduce learners’ misconceptions about the dissolved salts. The study also, explored students’ prior knowledge of concepts related to the dissolved salts and determined the effectiveness of POE strategy on males and females. A quasi-experimental design was used where the experimental group (EG) used POE strategy during treatment and where the control group (CG) used the traditional teaching using lecturing and demonstrations. Before the start of the study, both groups wrote a pre-test using the Achievement Test (AT) to determine science baseline knowledge. Thereafter the intervention for EG and lecturing for CG followed and lasted for five weeks. After the intervention, both groups wrote the post-test to determine learners’ achievements. The post-test was followed by interviews to discover issues that were not identified during the AT. The quantitative data were analysed using both the t-test and the Analysis of Co-variance (ANCOVA). The qualitative data collected through interviews were coded to form themes and later themes were organised in categories. The results show that EG performed better in the post-test than the CG their counterpart. More importantly, this study identified two new misconceptions that have not been reported in the literature: salts dissolve in water when it is in ‘fine’ grains; and solid sodium chloride is not an ionic compound. Furthermore, findings from AT revealed that students’ conceptual understanding of how salts are formed, how salts dissolve in water and how salts ionise improved dramatically especially from the EG, but not for the CG. Data collected on the AT post-test for EG show that males (mean 21.13 ± 9.72 SD) achieved better than females (mean 12.73 ± SD 5.97) and t-test p = 0.004. On macro level concepts, females from CG achieved higher scores than the males from the same group. Conversely, on micro level, the CG achievements were lower than the EG in males and females, suggesting that POE favours the reduction of misconceptions not only at macroscopic levels, but also at microscopic levels. The findings in this study highlight the need for educators, curriculum developers and textbook writers to work together in order to include various elements of POE in the curriculum as a model for conceptual change at high school science classroom.