Formal:
* Precocious: This implies learning at an advanced level for their age.
* Prodigy: This suggests exceptional talent and skill in a specific area.
* Gifted: This refers to having natural abilities and potential for learning.
* Rapid learner: This is a more general term for someone who learns quickly.
Informal:
* Quick study: This is a common way to describe someone who picks things up quickly.
* Sharp: This implies a keen intellect and ability to grasp concepts easily.
* Bright: This is a general term for someone who is intelligent and learns quickly.
* Fast learner: This is a straightforward way to describe someone who learns quickly.
Other options:
* Absorbent: This suggests someone who readily takes in new information.
* Receptive: This describes someone who is open to learning and willing to absorb new information.
Ultimately, the best word to use depends on the specific context and the impression you want to make.