"그는 도마에 양파를 잘라서 오븐에 넣었어요."
Translation:He cut the onion on the cutting board and put it in the oven.
"He cut the onion on the chopping board and put it in the oven." marked wrong. I'm getting marked wrong on what are just tiny variations in translation in this new Korean duolingo, I'm about ready to give up.
This course is in beta, so it's better to flag sentences with suggestions instead.