You added an extra み in 見ました
the correct one was "きのうのニュースを見た?"
Because, when you use the informal way of speaking, you better say "no" to ask a question.
"どこ行くの" => "Where are you going?"
When a formal way would be "どこに行きますか。"
But well, I don't think Duolingo has the informal speech saved in the database.
I said "昨日のニュースを見たか" and that got rejected. Seems perfectly grammatically correct though?
It would be in plain-form. The system seemed to be looking for "masu"form
Would 報道（ほうどう） be an appropriate translation of news?
昨日 not available