Originally Posted by boozehound
By not using the quotes properly, you are claiming them as your own sentences. Even if the prof knows you didnt realize it, its a fairly big deal. Citations are for referencing someone else's ideas in your own words.
Right. There's a big difference between a reference and a quote. There's a perception of honesty. If the professor thinks you're trying to bullshit him, you can understand why he would take 40%.
Perhaps you could try to convince him, it was an honest error and see if there's perhaps, an extra credit assignment you could do to make it up.