Here is the completed letter:
Dear Anya,
Hi! How are you? 1) I'm fine. I 2)'m at my new school! It 3) is great, but it 4) is very big. I like my classmates. They 5) are very friendly! I 6) 'm in Class 3B. This year, I'm doing maths, history and geography. The lessons 7) aren't very difficult, so I have a lot of free time. My favourite subject 8) is maths. My maths teacher 9) is very nice!
What about your school this year?
Love,
Wendy