Thank you notes are a must for all gifts you receive. These cards can also be used to show your appreciation for any service that has been provided to you. For example, if you are taking a dance class and your teacher goes out of her way to make sure you learn your steps, writing her a thank you note would be a nice gesture.
Write the salutation. If you and your teacher have a formal relationship, use "Dear" and their name. If it's more friendly, you can write "Hi" and their name, or just use their name.
Thank her for what she gave you in the first sentence of the card. If she took extra time with you on your steps or even just introduced you to the wonderful world of dance, mention that in your card.
Include a quick personal anecdote, if necessary. For example, "I have always had two left feet before I came to you and now I can tear up the dance floor."
Sign the card. You can use an ending such as "Yours Truly," "Sincerely," or "Thanks again." Depending on your relationship, your name might be sufficient. Make sure the signature is legible so your dance teacher knows who it is from.
Write the name and address of the dance teacher on the envelope. Place the card in the envelope, seal it and mail it to her.
Thank you cards by their very nature are quick notes showing appreciation. You don't have to make it a novel if your have a professional relationship with the teacher. If it is appropriate to write a longer thanks, by all means do so. However, it is not necessary.