S and V must agree

Students had a very difficult time identifying the subject and verb of a sentence—Luz, Viviana, Dominga, and Danny in particular. Luz said it might be because they've been out of school for so long and forget what these things are called.

Ericka and Evelyn understood the concept though and ended up being the "teacher" during an error correction activity. 

 

subtle, settle, subtitle

"what's" means "what is."