These problems and considerations lead to the following research questions.[br] [br][b]Question 1:[/b] What conceptions with particular attention to pre- and misconceptions emerge concerning functional thinking of students of lower secondary schools (grade 7/8)?[br] [br][b]Question 2:[/b] How should dynamic materials be designed to support students of lower secondary schools to develop appropriate mathematical understanding and thus to reduce errors due to pre-[br]and misconceptions concerning functional thinking?[br] [br][b]Question 3:[/b] What is the influence of dynamic materials on conceptions and internal representations of students of secondary schools particularly with regard to the understanding of[br]the co-variational aspect of functional thinking?

To answer the research questions, the following methods are chosen.[br][br][b]Question 1[/b][list][*]Diagnostic test 1 [br][/*][*]Diagnostic interviews (Zazkis & Hazzan, 1999; Hunting, 1997)[br][/*][/list][br][b]Question 2[/b][br][list][*]Literature on design criteria (Clark & Mayer, 2008)[br][/*][*]Observation: audio-, video- and screenrecordings[/*][/list][br][b]Question 3[/b][br][list][*]Observation: audio-, video- and screenrecordings[/*][*]Diagnostic test 2[/*][*]Diagnostic interviews[/*][/list]