A teacher spends an inordinate amount of time with their class and has a profound influence on them, not only imparting knowledge but wisdom and morality as well.
When writing a thank you note to teacher, keep it short and sweet, but make your gratitude known with sincerity. A heartfelt note means a great deal to a teacher and validates their efforts in class to change and influence the lives of their students.
Example: “If I hadn’t had you as a teacher, I don’t know where I’d be. You may not know it, but your classes have given me the self-confidence to follow my dreams. Thank you for that and know that you will be in my heart forever.” Taken from: https://tosaylib.com/thank-you-note-to-teacher/