If you wait until the end of the semester to touch base with students about what's working in your course and what's not, it's too late to make changes to enhance the learning process. Furthermore, it's too late for you to help students understand their responsibility as learners. Worse, it's far too late to help students see how your course connects to their professional and personal goals.
 
All of these interventions and adjustments are possible if you have a sense much earlier of where students are struggling, frustrated, or off the rails.
 
This midterm feedback poll template gives you a jumpstart for checking in with students when they need it and when you can actually use the results.
 
Bonus: See this article of mine for a detailed discussion of how this midterm feedback poll fits into a proactive, goals-centered alternative to relying on (and resenting) students' semester evals as your only metric for teachings success.