What is the evidence or proof that the middle class is shrinking?

1. What is the definition of middle class?
2. What is the evidence or proof that the middle class is shrinking?
3. What caused it?
Conclusion–answer the question: Why is the shrinking middle class important?
Introduction–what you will be discussing.
Due Date: Monday night midnight, February 21.

https://theworld.org/stories/2015-12-13/american-middle-class-shrinking

https://akcommonground.org/wp-content/uploads/2013/09/IFA-Screening-Discussion-Guide.pdf

https://www.documentarymania.com/player.php?title=Inequality%20for%20All
Read those for the essay
And watch the video