Is Bloom's "Two Sigma" phenomenon real? If so, what do we do about it?
As a tutor, my goal was to identify gaps and misunderstandings. Consider: how can you give a driver helpful directions if you don't know where they are?
As a student, I noticed that teachers are routinely ambiguous in ways they cannot understand. And mostly, these alternative interpretations work... mostly. So when they cause problems many layers later, the learner can see no clues to the cause. But an attentive tutor can.
Subtle gaps and misunderstanding have an outsize effect, and maybe could account for 2σ?
OTOH teachers accidentally trained me to disentangle ambiguity, and that is a valuable real-world skill.
The mentor relationship has magic in it and I remember the moment I learnt certain things. So maybe social aspects contribute too, as wiki suggests.
What to do? Like mandatory military service, mandatory tutoring service. We appear to be wasting obscene quanities of human capital. Imagine the economic productivity unleashed by a more fully realized workforce.
PS did pc receive one-on-one tutoring? Intelligent parents often tutor their children, conferring this outsize headstart.