David Kimura PRO said about 2 years ago on Gathering Questionnaire Responses :
1. The response instance variable looks to be nil in the snippet which is why you probably cannot link to the response show page. 

2. When are you trying to make the differentiation? Is it when pulling up a list of available questionnaires to take? If so, you could have an attribute on the questionnaire for the type of user. Something like "responder_type" and make it an enum. When listing out the questionnaires, you could query on this attribute depending on the actor (a lecturer or student).