Our pre-university chemistry students face problems achieving sufficient quality in chemical inquiry. To try to enhance the quality of student performance in chemical inquiry, Dutch pre-university chemistry students (age 17) carried out an authentic research project on 'Diffusion of ions in distilled water.' The learning materials for this student inquiry project, the teaching scenario and the website were designed in cooperation with five chemistry teachers. Three teachers from this network and two other teachers also implemented the project with 80 students to find out whether the emphasis on relevant concepts of evidence (CoE) improves the quality of student inquiry outcomes. This partwith its emphasis on the CoE -in the student inquiry task is based on four key features: the students feel motivated to explore, focus their attention on, give meaning to and reflect upon CoE. In teams students conducted a guide experiment, analysed a scientific article, did an inquiry and wrote a report, discussed CoE with peers on the Internet and rewrote their reports. All lessons were observed, field notes were made and analysed on whether the intended student activities had been realised. The Internet discussion was recorded in a database and analysed. The first and final reports of all teams were coded and analysed. Also the students' appreciation of the activities was assessed. The teaching and learning activities were realized to a very large extent as planned in the design. The emphasis on CoE resulted in 65% of the students achieving a sufficient level of quality in their final reports.
