A hand-written thank you card is a lovely and personal way to show your appreciation for your teacher's efforts. You could also consider giving them a small gift like a mug or a picture frame with a special message. If you have a particularly close relationship with your teacher, you could give them a more meaningful gift like a book they might enjoy or a special piece of jewelry. The most important thing is that your gift comes from the heart and shows your gratitude for their hard work and dedication.