What is considered "middle class" on CC?

My husband and I are working class people with upper middle class incomes. our kids right now are educated, middle class people starting their careers with the incomes of solidly middle class people. The last kid attends a prestigious prep school with upper class people who are mainly in the financial sector. You can just look at him and see the difference between him and my husband. We feel like we have succeeded beyond our wildest expectations.