Hi Malte,
The LAMS survey activity is meant to collect students responses for analisys and all, but it won't stop students for continue since there's no right and/or wrong answers.
However you can use the Multiple Choice activity which it does allow you to specify wrong and right answers as well as a passing mark. So if a student doesn't get to the passing mark, it won't be able to continue to the following activity in the sequence.
Have a look at the teacher's guide for specifics in each activity tool.
And can we remodel this behaviour with existing .LRN
survey / assessment?
Not with our current code base (LAMS v1.0.x). But as I mentioned before, LAMS 1.1 does have an API that will allow it to add external tools easier. There will be a few changes to the .LRN tools, but I don't think they will be significant.
LAMS 1.1 beta is expected to be released in the firt quarter of 2006.
Ernie