University students' retention of derivative concepts 14 months after the course: influence of 'met-befores' and 'met-afters'

This article reports the concluding part of a larger study on retention of key procedural and conceptual concepts in differential and integral calculus among Croatian and Danish university students in non-mathematics study programmes. The first parts of the study examined the retention of the students' knowledge through a questionnaire testing core calculus concepts in derivative and integration given two and six months after the students had passed an exam testing those concepts. In the present article we continue to explore the retention of core concepts in derivative through a mixed method approach examining the knowledge of 10 second-year non-mathematics students 14 months after they took the course. The result showed that there were several negative met-befores and met-afters affecting the students' retention.