If you will conduct pedagogical research fairly often in your classes, you may wish to include a statement such as the following to your syllabus:
I consider my teaching a scholarly endeavor: what I learn from you in this class can help me improve future courses. I may even draw from your assignments to create scholarship that helps others wishing to improve their pedagogical (teaching) practices as well. If I do so, your identity (name or other identifiable information) will remain anonymous. If you have concerns, please speak with me.
Or, if you wish to use more extensive information, direct quotes, etc. from course assignments or reflection pieces, you may wish to consider printing and obtaining signatures on a minimal informed consent statement such as the following:
Purpose of Project:
Our unit on [topic] is part of my ongoing scholarly project to investigate [research objective].
By signing this form, you give me permission to use your informal, reflective, and formal writing in my research on [topic]. For the examples I choose, I will be using pieces of your writing and you will be anonymous.
If you don’t wish to grant permission, that choice will not affect your grades in this course.