Attached is three letters that I use with my parents. The first being a welcome letter, telling a bit about myself and what to expect, the second thanking them for the gifts (could be used for teacher appreciation week or winter break gifts), and the last at the end of the year thanking them and wishing them well in their future. You can customize these as you like, adding your own personal touch. I find it helpful to have a template to start with so I hope you find this useful!