I have confused. I know that a "student" in USA is a person who is studying at school, college, or university. But there is a difference in Russia - a person who studies at school calls "pupil" - "ученик" (masculine, single) / "ученица" (feminine, single). A "student" - "студент" (masculine, single) / "студентка" (feminine, single) in Russia is a person who is studying at a university. I think there is a difference in semantics of the words. My opinion - the right answer for "ученицы идут в школу" is "(the) pupils are going to school".
According to dictionaries, a pupil is someone under the direct supervision of their teacher. You could argue that every pupil is an ученик, but not every ученик is a pupil. Moreover, the word "student" can mean both «ученик» and «студент» in English, so the suggested translation seems absolutely correct to me. The German course does the same, actually, you can translate all four (Schüler(in), Student(in)) as "student".
Russia isn't the only place to make that distinction. In the UK student is not used for children at school either. They are pupils. They go to school. Students don't.
By all means accept students for american english speakers but pupils should not be rejected. I have already reported it several times.
I think this is the best thing about Duolingo - you get the basics from the course but if you delve into the comments section you find ALL of the subtleties.
Or at least it's that way with the Russian one. There are several of you chiming in, explaining and challenging and I think it's great. Thank you.
It is interesting that Google Translate leans into that ученитси is apprentices while ученики is translated there as students, pupils. But in the comments, some suggest students and pupils are different. I would like to see how "the student has now become the master" is interpreted into Russian. :-)