My kids are in lockdown homeschooling, and sitting in on some of the live lessons you can see the cracks - very slow, kids moving at different paces, and much much harder for teacher to see who is keeping up and not.Yet my recently hired collegue insists he spent more time learning from Youtube than from lectures at "proper" university.There is quality "content" out there - but how do we ensure "mastery" is achieved (ie the concepts understood).  It seems quite feasible but who is working on it? What are the impacts when we go back to normal?What as time constrained parent should I look at? (beside spending "quality" time with them. They don't like that :-)PS 
There are seemingly complete areas like thenational.academy or khanacademy but I am not sure how they linknsubjects to syllabus (especially US/UK syllabuses)