Wallin, Anita2009-01-272009-01-272008http://hdl.handle.net/2077/19220A teaching-learning sequence about the theory of biological evolution was developed by linking theoretical reflection, instructional design and classroom research in a cyclic process. Altogether 79 students participated in three trials of this sequence. The students aged 17 – 19 had all chosen the science branch of upper secondary school in Sweden. Before teaching started the students were given a pre-test and, one year later, a post-test. Each students’ entire pre- and post-test were categorised into one of four categories. The categories were: consistently scientific; mainly scientific; mainly non-scientific; and consistently non-scientific. In the post-test, 43 % of the students used the scientific theory of evolution consistently throughout the test compared to 6 % in the pre-test. 60 % of the students were categorised as using non-scientific ideas consistently in the pre-test and 5 % in the post-test. 30 students changed their way of reasoning between pre- and post-test in such a profound way that one may speak of conceptual change. The analyses of the students’ performance revealed that students who partly used scientific ideas in the pre-test did not demonstrate a more consistent use of scientific ideas in the post-test than students starting with exclusively non-scientific ideas.engconference paper, peer reviewed