"Is Kateřina a woman or a little girl?"

Translation: Je Kateřina žena nebo malá holka?

[ftk20]

Thanks for the clarification. And thank you for all the work you and the Duolingo team have done to create this program for Czech language. I'm enjoying my learning time a great deal!

[ftk20]

We didn't yet learn about diminutives for word like devce; using devcatka as the correct answer rather than explaining the difference between devce and holka for "little girl" wasn't helpful...

[VladaFu]

That is how Duolingo works. It will offer you any valid translation it thinks is the closest to your try. And we do have to include all valid answers, not just those already learned.