Looking on the internet deeply has found these results:

they aren't classmates is the most popular phrase on the web.

they aren't classmate 10 results on the web	they aren't classmates 14 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	2010?12?7? ... B. They aren't classmates )14. Who's the boy on the right in the photo? 1 C. He's happy. C. She's Millie. C. Yes, they are. ????? A. He's�... Aug 11, 2006 ... (A/U Since they already in Middle school and in a new semester they aren't classmates anymore, they have different sections). As Mikan was�... 2015?4?27? ... But they aren't classmates. Jane is in Class One. Miss May is her teacher. Mary is in Miss White's class. They study Chinese. They like it. May 1, 2015 ... They aren't classmates of a governor. The parents of Death Avenue are looking for ways to get their children far away. Armoni Sexton's mom�...

they aren't classmate

10 results on the web

they aren't classmates

14 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

2010?12?7? ... B. They aren't classmates )14. Who's the boy on the right in the photo? 1 C. He's happy. C. She's Millie. C. Yes, they are. ????? A. He's�...
Aug 11, 2006 ... (A/U Since they already in Middle school and in a new semester they aren't classmates anymore, they have different sections). As Mikan was�...
2015?4?27? ... But they aren't classmates. Jane is in Class One. Miss May is her teacher. Mary is in Miss White's class. They study Chinese. They like it.
May 1, 2015 ... They aren't classmates of a governor. The parents of Death Avenue are looking for ways to get their children far away. Armoni Sexton's mom�...