Why not design the proposed online survey using the actual survey tool?
Students use the tools they are most comfortable with. If the excercise does not limit the tools, then that is only right. In my field (sociology)  most of them have put many many many more hours in Word or Excel then in some survey tool, so if this were an excercise for my students I would expect to see the pattern you report. If I wanted them to get experience in the survey tool, I would need to change the text of the exercise to require them to use that tool.