adjective
apt
Quick to learn or understand.
The apt learner quickly fits the puzzle piece.

Etymology
Latin aptus means fitted or suitable. Applied to a learner, that fitness becomes readiness and ability to grasp or acquire something quickly.
In context
without a good subject the epistle will be apt to be dull
More examples
- She proved an apt pupil.
- He was apter at the task than expected.
- The apt student understood immediately.
Forms
apt · apter · aptest
aptitude noun — a natural ability or readiness to learn