Three quick steps:
- Critical Theory in general was developed by academics in the mid-1900s.
- Sub-species were developed in the late 1900s, among them Critical Legal Theory, Critical Race Theory, Critical Feminist Theory, and more.
- Shortly thereafter, an increase in academic work on Critical Theory applied to education. That culminates in these books published early 2000s:
Foundations of Critical Race Theory in Education, first edition published 2009.
Handbook of Critical Race Theory in Education, published in 2013.
Within a decade, the results go public big time. Hence the current education battles.
Related: Critical Theory is one of the feeders into a broader postmodern philosophical framework. Hence obligatory mention of my Explaining Postmodernism: Skepticism and Socialism from Rousseau to Foucault.