adjective
active
A2
'Active': describes someone/something engaged, functioning or participating. Common antonyms: passive, inactive. Gradable: comparative 'aktiver', superlative 'am aktivsten'. Not a past participle. As an adjective, it inflects by gender, number and case (ein aktiver Teilnehmer, sie ist aktiv). No specific preposition required.
Examples
Die Freiwilligen blieben aktiv, obwohl das Programm schwieriger war als erwartet.
The volunteers remained active, although the program was more difficult than expected.
Er ist sehr aktiv und geht jeden Morgen joggen.
He is very active and goes jogging every morning.
Details
Mnemonics
Picture someone jogging and being active — the word 'aktiv' looks like 'active' in English.
Notes
Gradable adjective: can form comparative and superlative. Common in descriptions of people and programs.