活発

1. Origins, structure, and basic meaning

• Structure: 活発 (かっぱつ) is a na-adjectival expression for energetic movement or vigorous exchange.
• Basic usage: 活発に動き回る adverbially modifies children’s energetic movement, while 活発な議論 attributes vigor to discussion of a new proposal.

2. Common pitfalls and similar expressions

• Physical activity and vigorous discussion
  • 活発に動く concerns bodily motion, whereas 活発な議論 extends the idea to frequent exchange. It does not mean that discussants are running around.