It all depends on which American Dream you're talking about.
When I Google the American Dream, a website defines it as "...the belief that anyone, regardless of where they were born or what class they were born into, can attain their own version of success in a society where upward mobility is possible for everyone."
This isn't true. It just isn't.
In a perfect world, the dream itself doesn't change, but the rules we have in place to keep specific groups of people lower than others do. I personally believe it can't. I do think it is achievable without hard work; specifically if you aren't a minority, and born into a rich family. But, this is just my personal opinion.
Answer:
1: Taking a sentence from a book and not stating the author.
2: Copying someones essay or test.
3: Taking a definition from Wikipedia and not stating that you got it from Wikipedia.