Hi Susanne,
The Questionnaire tool was last worked on some time ago (2016). It was intended as a way for students to enter results of experiments. It was designed to have a sequence of two questionnaires: the first general information about the experiment, the second (which repeats in a loop), the results of each of several trials. The data that is gathered by the plugin is transferred to a CODAP dataset. There, the student can use CODAP tools to analyze the data. If this is similar to what you want to accomplish, then this tool may be useful to you.
Students could, of course, enter data directly in CODAP tables. The Questionnaire plugin is meant to provide the opportunity for a more guided experience.
Jonathan