The research question are examined in more detail by means of a qualitative hypothesis generating case study. Therefore the GeoGebra applets are used in a 7th grade of a middle school in Austria. The qualitative analysis is carried out using methods of Grounded Theory (Glaser & Strauss, 1998).[br][br]The data collection is divided into a process that involves five stages.

[list][*][b]Stage 1: Diagnostic test 1[/b][br][list][*]Contains tasks concerning different pre- and misconceptions;[/*][*]Then students are divided into 2 groups;[br][br][/*][/list][/*][*][b]Stage 2: Diagnostic interviews[/b] [br][list][*]Concerning tasks from diagnostic test 1;[/*][*]With 8 students of group 2;[br][br][/*][/list][/*][*][b]Stage 3: Intervention[/b][br][list][*]Use of GeoGebra applets in class;[/*][*]Students working independently in pairs;[/*][*]Duration: 3 lessons;[br][/*][*]Recording (audio, video, screen) of students of group 1;[br][br][/*][/list][/*][*][b]Stage 4: Diagnostic test 2[/b][br][list][*]Contains tasks concerning conceptions slightly different from diagnostic test 1;[/*][*]With all students;[br][br][/*][/list][/*][*][b]Stage 5: Diagnostic interviews[/b][br][list][*]Based on analysis of recordings and diagnostic test 2;[br][/*][*]With 8 students of group 1;[br][/*][/list][/*][/list][br]If necessary interviews with teachers about the design of the applets will be conducted.

Here are some tasks of the diagnostic test 1. The first two tasks (Area, Skier) are according to examples from Schlöglhofer (2000). The third one is from a german test instrument called CODI, which has been designed by Nitsch (2015) to diagnose misconceptions concerning functional relationships.

[i]You see a skier who is descending a slope. The graph shows the speed of the skier in the course of time. Which of these 4 diagrams is describing the situation best?[/i]

[i]Here a trapezoid is displayed. Imagine you draw the dotted line from vertex A to the right by the distance x. In doing so you observe the changes in the size of the grey marked area. [/i]

[i]In the diagram the grey-shaded area is a function of distance x. Which of these 4 diagrams is correct?[/i][br][br]

Which of the 4 cars is the fastest at the time t = 5 seconds?