"Die Lehrer prüfen mich, ich weiß noch nicht wie."
This is ridiculous. I put "I still do not know how the teachers are testing me" and they said I was wrong and gave me a sentence that says the same thing but in a horrible way: "The teachers are testing me, I don't know yet how." ??
welcome to Duolingo :)
Seriously, this also happens all the time to me. However, I think you should report this, and see if they accept your sentence as correct, as well.
although noch=still and nicht=not, .... "noch nicht" go together to mean "not yet" so the correct answer should have "yet" somewhere
It sounds odd in English but it probably should be accepted. Just report it.