Teacher’s Appreciation Letter Analysis

Consider the following excerpt from a letter written by a teacher to the parents of her students:

"Dear Parents, I want to express my gratitude for the support you've shown this year. It has been a challenging yet rewarding experience for both teachers and students. Your involvement has made a significant difference in enhancing our classroom environment and fostering a love of learning. I look forward to our continued partnership in the education of our children."

What is the primary purpose of this letter?