I don't have an academic reference about this but it seems very problematic and in my institution I am sure that the ethic committee will not permit it. I didn't get a permission to distribute questionnaires to my students (for research purposes).

Hi, Ahmed,

Research with human subjects absolutely requires informed consent in the U.S., and this is even more important when the subjects are under the authority of the researcher because of the potential for coercion.

Dear Tehila and Peter 

It's great to win your invaluable answers. Really I appreciated that, but I meant that kind of action research, which conducted to upgrade the teaching/learning performance. So the class chosen is a part of primary stake holders. 

Ahmed,

The research methodology is irrelevant. If the data collected is for dissemination in publications, informed consent is required.

Dear Peter, 

Thanks again, what you have stated is inarguably  right. however there is a  philosophical school of research (Pragmatism) claims that you can use whatever works to collect your data. Particularly when you want to collect real authentic data. So, can you please tell me a little about your  opinion on above school!

Kind regards