Thanks for your reply. It seems like that part of FluentU is concentrating on building vocab, but throwing in incorrect grammar just to confuse everything!
I had another completely different query, but it seems a bit unnecessary to start a new topic. "Man kann ja nie wissen" - Why is there a "ja" in the middle? I've asked two German speakers and the answer I've been given is that in this context "ja" is more of a sound than a word, but it still confuses me.