It's necessary to get student feedback if you want to become a better teacher. Student evals are often done at the end of the course. However, if you can get your hands on the evaluation sheet ahead of time and give them out during mid-terms you'll be able to nip any problems in the bud. It may also change your teaching style and help your students out even more.
If you have high student evals, you have a better chance of getting renewed. There are a number of things you can do to help boost your student evals, but I've found the best thing to do is to ask students.
I create an open-ended questionnaire that I give out to students during mid-term week. They fill it out in class either in groups or individually. It's anonymous and I explain I want their feedback in order to make the class better.
I've found it to help out immensely. I'm glad I ask students for feedback and I know that changing my lessons will help make me a better teacher. It has also helped my student eval score so it's a win-win for everyone involved.
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