Push the "why" until you hit what you don't know

Keep asking why of your own answer until you reach a gap, then go fill it.

Why it works

Each "why" answered invites another "why" of that answer. Chaining them surfaces the exact point where your understanding stops — the boundary of real comprehension. Finding that boundary is valuable in itself: it converts a vague feeling of knowing into a specific, fixable gap, which is where further study pays off most.

How to do it

1. Answer the first "why", then ask "why is that true?" of your answer.
2. Continue until you reach a step you cannot justify.
3. Mark that gap as the next thing to learn rather than papering over it.

Evidence

Self-explanation research finds that learners who explain more deeply detect their own comprehension gaps and revise their mental models, which improves understanding and transfer beyond rote retention. (rct)

Deep self-explanation helps most when feedback or a source is available to fill the gaps it reveals; surfacing a gap without resolving it does not by itself improve learning.

Common mistake

Stopping at the first comfortable answer, which hides the gap instead of exposing it and leaves the shaky part of your understanding untouched.