This should be stereotyping because it would be implying that all people of that age, occupation, race, or similar, are the same and belong in the same group.
No they aren't proper to use in writing class they are considered slang. It would show your teacher that your not interested in sounding educated and proper.
Hope this helps!
Answer:
a is the ansewer i thinlk look it up and sorry my key boeard is messing up i know how to spell.
