Time on task is the duration a learner spends on a piece of content. Raw elapsed time is close to meaningless; the useful form is focus-adjusted, subtracting periods where the window did not have focus.
What it is
Most platforms report elapsed time — the interval between opening and closing. That interval includes lunch, meetings and everything else that happened while the tab sat open.
Focus-adjusted time uses the Page Visibility API and focus/blur events to accumulate only genuinely attended time. On real deployments the two figures frequently differ by a factor of two or more.
Why it matters
It is often the first metric people reach for and the one most likely to mislead. Focus-adjusting it usually causes reported engagement to fall sharply, and that fall is information rather than regression.
A common confusion
Long time on task is not automatically good. It is equally consistent with confusion, distraction, or a background tab. Pair it with assessment performance before interpreting.
Related
See also engagement index, cognitive load and completion rate. See the full glossary for the rest, or beyond completion rates for the wider context.
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