"Students see the Chinese teacher at noon."
No, but Duo often marks it as wrong. It's like saying, "they see teacher noon." You need the 在 to say "they see the teacher AT noon." I report this issue A LOT and they have corrected a few of them.
It says the correct version is that the students 说话 at noon but the English says "see" the teacher at noon. See and speak with are subtly different especially when most of this lesson uses 见 for see.