I'm a professional instructor (though not related to aviation). As such I regularly have to study new material for which no course material or courses exist. (In fact, in quite a few occasions I'm the one tasked with writing the course material.)
The best way for me to validate I understand the material is to find an empty classroom, and start explaining the material in my own words to an (imaginary) audience. (Even the empty classroom is imaginary, most often, but you get my point.)