Bayram Coştu

Evaporation in different liquids: secondary students’ conceptions

This study explores secondary school students’ understanding of evaporation and investigates whether students associate the concept of evaporation with only water as a liquid. An open‐ended written test was developed using three different words (water, liquid or alcohol) to state the question phrases. The test was implemented on a sample of 313 students at different levels of schooling. Clinical interviews, in which ethyl alcohol was used as an example of liquids, were also undertaken with 12 students, either individually or as a group. From the collected data, it was found that most of the students at different levels lack understanding of the concept and have several misconceptions. Various misconceptions of the evaporation concept that differ from those cited in the related literature were determined. The most important result was that students’ written responses showed some specific misconceptions when they were presented with the questions using three different words; liquid, water and alcohol.

Promoting conceptual change in first year students’ understanding of evaporation

We constructed the PDEODE (Predict-Discuss-Explain-Observe-Discuss-Explain) teaching strategy, a variant of the classical POE (Predict-Observe-Explain) activity, to promote conceptual change, and investigated its effectiveness on student understanding of the evaporation concept. The sample consisted of 52 first year students in a primary science education department. The students’ ideas were revealed by a test consisting of eight questions. The PDEODE teaching strategy was designed on the basis of the students’ preconceptions. Conceptual change in students’ understanding of evaporation was evaluated by administering the same test as pre-, post and delayed post-test. The test scores were analyzed by both qualitative and quantitative methods. Statistical analysis using general linear model repeated measures of student test scores point to statistically significant differences in pre-, post-, delayed post tests and total scores (p<0.05), suggesting that the strategy helped students to achieve a better conceptual understanding. Further, no statistically significant differences were observed between post-test and delayed post-test scores, suggesting that teaching strategy enabled students to retain their new conceptions in their long-term memory.

Presentation of atomic structure in Turkish general chemistry textbooks

Research in science education has recognized the importance of teaching atomic structure within a history and philosophy of science perspective. The objective of this study is to evaluate general chemistry textbooks published in Turkey based on the eight criteria developed in previous research. Criteria used referred to the atomic models of Thomson, Rutherford and Bohr and twenty-one textbooks (published between 1964 and 2006) were analyzed. Results obtained showed that none of the textbooks explained satisfactorily that: a) Thomson’s experiments on cathode rays were conducted to clarify the controversy with respect to the nature of cathode rays, that is, charged particles or waves in the ether; b) The rivalry between Rutherford’s hypothesis of single scattering based on a single encounter and Thomson’s hypothesis of compound scattering led to a bitter dispute; c) Bohr had not even heard of the Balmer and Paschen formulae for hydrogen line spectrum when he wrote the first version of his article; and d) Bohr’s model was based on an inconsistent foundation in which he ‘grafted’ Planck’s ‘quantum of action’ on to Maxwell’s electrodynamics. Some textbooks explained satisfactorily that: a) Rutherford’s model of the atom had to compete with that of Thomson; and b) Bohr’s main objective was to explain the paradoxical stability of the Rutherford model. It is concluded that the inclusion of historical reconstructions of atomic structure in Turkish general chemistry textbooks can provide students with a better appreciation of the dynamics of scientific progress.