A Good New!

Watching the mistakes that my students make often shows me just how stupid the English language is sometimes.

In their recent midterm, one of the prompts they could choose was writing a letter to tell a friend about winning a contest.

Many of my students used this phrase in their letters: "I have a good new..."

It took me a second that what they meant was "I have some good news".

It kind of makes sense, though, right? If you have a lot of wonderful things to tell someone you would say:
"I have some/a lot of good news!"
but if you only have one thing to talk about, shouldn't you be able to say:
"I have a good new!"

It's kind of like the eternal question of if you have a bunch of odds and ends and you get rid of all but one...what do you call it?