|Scharfenberg, F-J: Experimenteller Biologieunterricht zu Aspekten der Gentechnik im Lernort Labor: empirische Untersuchung zu Akzeptanz, Wissenserwerb und Interesse (am Beispiel des Demonstrationslabors Bio-Gentechnik der Universität Bayreuth mit Schülern aus dem Biologie-Leistungskurs des Gymnasiums), (2005)|
Based on theories of development-orientated evaluation research, an experimental module was developed relating to aspects of gene technology. It was offered to classes as an experimental workshop in an out-of-school educational laboratory. The day-long teaching unit consisted of four authentic experiments: (i) transformation of bacteria with a recombinant plasmid coding for GFP; (ii) isolation and restriction analysis of the plasmid and (iii) visualization of the results by agarose gel electrophoresis. Experimental work was coupled with an ethical reflection unit regarding gene therapy. The study was of a quasi-experimental design, with one group doing experiments and two control groups doing no experiments (one at school, one at the lab). An additional external control group without any intervention was also included in order to survey potential pre-test effects or other external influences. Altogether, 363 12th graders (secondary school, 29 A-level courses) were assessed with regard to acceptance, increase in knowledge, and interest in gene technology. To this end a questionnaire was developed and tested in a pilot study (172 pupils, 12 courses). A pre-, a post- and a retention test were done. Scores for acceptance, increase in knowledge, and interest were calculated and evaluated as regards differences between the groups using the quantitative test theory and, in the case of increase in knowledge, by additionally applying latent class analysis. The two independent variables (learning location, experimental work) revealed the following influences on the three constructs tested: Current and retrospective acceptance of teaching with experiments in the out-of-school lab showed significantly higher scores in comparison with non-experimental instruction on the same themes, independent of the learning location. “Affective rating” and “rating of lesson related actions” could be identified as significant acceptance factors. Acceptance of the experimental unit is based primarily on the hands-on activities, while acceptance of the non-experimental lessons depends on aspects such as content, instructional methods, and the teacher as a person. The subtest knowledge increase was divided into two parts by means of latent class analysis: “prior knowledge” items and “project-oriented” items relating to new themes. The pupils were divided correspondingly into learner types. Pupils of all groups increased their knowledge either as a whole or in relation to the project, while an improvement in “prior knowledge” items was revealed only in the lab independently of whether experiments were done. Part of the pupils’ knowledge persisted, another part was forgotten. Additionally, the stimulation of knowledge increase in the lab situation is shown by a significantly higher proportion of learners in comparison with learning at school and the lack, or, as the case may be, the only partial existence of positive correlations between achievement in learning variables and prior achievement at school. Actual learning success was significantly higher in the group which performed experiments as regards knowledge acquisition as a whole, and in the non-experiment lab group as regards the actualisation of prior knowledge, both of these in comparison to the school group. The special importance of prior knowledge in the experiment group was revealed by their significantly higher proportion of project-related learners as well as by positive correlations - only shown in this group - between achievement in learning performance and experience of demonstration-experiments (by teachers) in school. On the other hand, in the experiment group the score for overall and project-related forgetting was significantly higher than in the school group. The results suggest, on the one hand, a possible increase in learning motivation in the lab, furthered by the performance of experiments, and on the other hand, they comply with the cognitive load theory in that they possibly indicate a higher extraneous load for the pupils in the experimental situation. The high interest in aspects of gene technology is differentiated into interest in “human applications” and applications in “Green gene technology” as well as its “ethical aspects”. Results showed changes in interest only in the girls. In the experiment group the decrease of interest as a whole was significant in comparison to stability of interest in both non-experiment groups. Similarly, in the experiment group the stability of interest in ethical aspects was significant in comparison to the corresponding increase in the groups without any experiments. The expected stimulation of interest through the performance of experiments cannot be confirmed. Additionally, consequences for the teaching of science were derived with regard to demonstration-experiments at school, preparation of pupils for a visit to an out-of school lab and such experimentation as part of a teaching framework in the lab.