I would use both, a check box AND a continue button. Otherwise people click on the checkbox accidently and then go already to the next page.
For that, follow the next steps:
- put the following code in a html field and put it on the top of the first page of you questionnaire:
- create a question (I used "Mehrfachauswahl", a question where you can select multiple options). Do not enter a question, but only write the text you need in the item text.
- Then put the question on your page. Above it, use the following code:
border:2px solid #555;
Copy it in a php- field.
That is obviously just one way to do it.