school of hard knocks

The School of Hard Knocks is an idiomatic phrase meaning the (sometimes painful) education one gets from life, often contrasted with formal education. It is a phrase which is most typically used by a person to claim a level of wisdom imparted by life experience, which they consider at least equal in merit to academic knowledge. It is a response that may be given when someone is asked about their education, especially if they do not have an extensive formal education but feel they have work/life experience that should be valued instead. It may also be used facetiously to suggest that formal education is not of practical value compared to work experience. In the UK, the phrases University of Life and School of Hard Knocks may be used interchangeably.
See more at Wikipedia.org...

ordinary experiences of life He learned all about life in the school of hard knocks.